University of Washington
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Erin M. Flynn
Homeostasis Unit Matrix
10th Grade Biology
March 24, 2004
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Subject area description:
The topic of this unit of instruction is homeostasis; it will be the first unit of the school year. The purpose behind starting the year with a unit such as this is that at the high school where I will be teaching Biology (Inglemoor High School in Kenmore), they have traditionally began the year with a unit on “Basics of Biology: Cells,” and I decided that this is not an ideal way to begin a biology class. It is more appropriate to begin the year with a unit that studies a phenomenon like homeostasis, which can be examined in a variety of ways that can be more readily seen as related to students’ lives and thus a more engaging way to begin the course and set the tone for the remainder of the year. It is difficult to begin the school year with the students studying the structure and functions of cells, which are microscopic, basic units of life. Students who are unfamiliar with biology may not appreciate the importance of cells if they do not have any context in which they can understand that cells are essential for all living organisms. I will approach homeostasis from two levels: the organismal and the cellular. This unit will directly lead into a unit on the structure and function of cells, which was originally planned to come first. The students who will be learning this material will be 10th graders, both “honors” and “non-honors” students, native and non-native (ELL) students, and students with IEP or 504 plans, all mixed in the room (the school is generally untracked with the exception of the IB program, which I will not be teaching). Hopefully the students will come into my classroom with some Life Science experience from Junior High, as well as some background in the scientific method; but I will be prepared to back up and support the students’ learning if I ever hit a roadblock in students understanding due to lack of background. Since it is the beginning of the school year, I will assume that students come to class with a rusty mind that I will need to lubricate to get working properly (after the long summer months!). I will do this through engaging students in a variety of hands-on activities and introducing scientific inquiry (to norm this type of “doing science” early on). One thing to keep in mind is that Inglemoor is on a semi-block schedule; each class period meets Monday and Friday for 53 min., and meets two of the three “middle days” (Tuesday, Wednesday, Thursday) for 75 min.
Essential questions and content and skills necessary to answer the EQ’s:
1. Why don’t we (as healthy individuals) overheat and get very sick when the temperature in Kenmore reaches 110°F during a 6-day heat wave in mid-August (assume we do not have air conditioning)?
In order to answer this question, students must understand how the human body responds to changes in ambient temperature. They must have a conceptual understanding of how sweating is involved in maintaining homeostasis in the body. They must also understand that the difference between the average resting temperature of a human (98.6°F) and the temperature of the environment must be small enough for the body to compensate for the difference without resorting to the use of external “equipment” (i.e. a cool swimming pool in the heat, a down jacket in the cold) to help regulate core body temperature or the chance of survival is slim.
2. How does your body physically respond to strenuous exercise? In other words, what exactly is happening inside your body when you are running around while participating in your favorite sport?
This question allows the student to expand upon his/her knowledge and understanding from question #1, so understanding thermoregulation by sweating is essential to answering this question. It will also be important to understand that there will be an imbalance in osmoregulation of the cells in the body if water is not consumed to replace what evaporates through sweating. The student will also delve into the digestive and circulatory systems and understand their cooperative role in bringing available nutrients to the muscles, whose nutrient stores have become depleted as a result of exercise. Students must also able to understand the interplay between the respiratory system and the circulatory system for the continual delivery of oxygen to the cells (utilized during cellular respiration, increased in muscle cells during exercise).
Learning goals and objectives:
1. Students will analyze systems, including inputs and outputs. (EALR 1.2.1)
1.1 Students will understand that homeostasis is a state of balance, where the system (be it an organism, tissue, organ, or cell) responds to changes in the environment (internal or external) by making adjustments within the system in order to regain that balance.
1.2 Students will know that the human body responds to physical exercise by increasing heart rate, and that this rate will return to “normal” following an appropriate rest period.
1.3 Students will understand that temperature regulation in an endotherm is an example of homeostatic balance, and be able to explain this phenomenon through this lens.
2. Students will explain how organisms can sustain life by obtaining, transporting, transforming, releasing, and eliminating matter and energy. (EALR 1.3.7)
2.1 Students will apply the principle of homeostasis to the human body’s responses to strenuous exercise, including the transport of oxygen and nutrients to the working muscles of the body.
2.2 Students will demonstrate understanding of diffusion across a selectively permeable membrane.
2.3 Students will demonstrate understanding of the phenomenon of osmosis.
2.4 Students will know the difference between osmosis in a plant and animal cell.
3. Students will design, conduct, and evaluate systematic and complex scientific investigations, using appropriate technology, multiple measures, and safe approaches. (EALR 2.1.2)
3.1 Students will understand how to create scientifically valid hypotheses.
3.2 Students will understand how to create and revise a scientific model based on their hypothesis and data analysis.
3.3 Students will understand that conclusions must be based solely on the data collected during experimentation; any claims outside of this data are unsubstantiated.
4. Students will learn to become more scientifically literate citizens and apply their knowledge to situations occurring in every day life.
4.1 Students will know that equilibrium is a ubiquitous concept that is important to the smooth workings of many systems in “the real world.”
4.2 Students will be able to explain osmosis by referring to examples in their everyday life.
5. Students will display skills important to “doing science” in an authentic setting.
5.1 Students will learn to work well with their peers through group work.
5.2 Students will learn to safely handle equipment and chemicals in the lab.
5.3 Students will express ideas through oral and written expression (EALR 2.1.5).
5.4 Students will defend their scientific conclusions or arguments (EALR 2.1.5).
Unit matrix
|Day 1: Building a knowledge base for “equilibrium” (53 min.) |
|1. What students are doing |Students will watch a demonstration by the teacher of a simple see-saw balance in |
| |equilibrium, and then in an imbalanced state. Students will explicitly describe |
| |(through class discussion) what caused the imbalance in this system, and suggest ways |
| |to rebalance the see-saw. In groups of 4, students will brainstorm ideas about |
| |situations in life where equilibrium is important (e.g. a bank, a supermarket, etc.). |
| |Students will then write a paragraph summary of their ideas and share with the class. |
| |Remind students at the end of the period that they must be prepared to do some |
| |exercise in tomorrow’s class (dress appropriately). |
|2. Objectives |4.1 Students will know that equilibrium is a ubiquitous concept that is important to |
| |the smooth workings of many systems in “the real world.” |
| |5.1 Students will learn to work well with their peers through group work. |
|3. Reasons for content and instructional strategy |This is the first instructional unit of the school year. I am working with the |
| |assumption that the students will not have much detailed knowledge of biological |
| |principles such as homeostasis, so my intention is to scaffold their understanding in |
| |small steps. I begin by using a simple example of a balance (the “hook”), which most |
| |students will likely be able to explain. Then, I will get the students to think in |
| |more depth about examples of equilibrium that they bring to the classroom (eliciting |
| |students’ ideas); I can draw parallel information from these examples in future |
| |lessons when I introduce the concept of biological equilibrium, or homeostasis. I |
| |also want to make working in groups a norm in my classroom, so I begin this on day |
| |one. It is important for students to learn to gather ideas from each other and come |
| |to a group understanding or explanation of a phenomenon. This is a skill that will |
| |help them in life, in science or wherever their future takes them. |
|4. Evidence of understanding |Students will present their ideas to the class. This will make it explicit to me |
| |whether or not they understand the idea of equilibrium. Students will fill out a |
| |self-evaluation on their group work skills for the day which will be kept in their |
| |portfolio. |
|5. Resources |Simple balance (can be made from a ruler balanced upon a triangular block); wooden |
| |blocks of various sizes (for demo). Manila folders for each student to begin his/her |
| |portfolio. Handout of criteria for group work (one per student). |
|Day 2: What happens during exercise? (75 min.) |
|1. What students are doing |Students will participate in small group discussions (the same groups of 4 from day 1)|
| |about the following question: “How does the human body maintain its weight? Explain |
| |how one could go about losing weight, and how one could gain weight (and, more |
| |importantly, why this occurs … thinking back to our group work yesterday),” (eliciting|
| |student ideas). |
| |Students will do a small inquiry activity that introduces the concept of homeostasis |
| |in our own bodies. As part of a class discussion, students will answer the question, |
| |“What changes do you notice in your body after you do a shuttle run in P.E. class?” |
| |(Phase I- building a knowledge base). In pairs, students will make a prediction about|
| |what will happen to their heart rate after exercising, and what will happen over time |
| |while they rest following activity. They will diagram a simple model that represents |
| |their hypothesis (Phase II- hypotheses & initial models). Then students will make a |
| |data table in which they will collect data for their heart rate at rest, after 10 |
| |jumping jacks, after 20 jumping jacks, after 30 jumping jacks, and after 3 – 30 sec. |
| |intervals of rest, or until their heart rate returns to its original resting rate. |
| |Each student will collect data about his/her own heart rate. In the first trial, one |
| |student measures and collects data and the other exercises, then they switch roles for|
| |the second trial (Phase III- conducting the investigation). Students will consider |
| |their data sets and determine whether their hypothesis was accurate (Phase IV- |
| |analyzing data), and will make any necessary revisions to their model (Phase V- |
| |reconsidering the model). |
|2. Objectives |1.2 Students will know that the human body responds to physical exercise by increasing|
| |heart rate, and that this rate will return to “normal” following an appropriate rest |
| |period. |
| |3.2 Students will understand how to create and revise a scientific model based on |
| |their hypothesis and data analysis. |
|3. Reasons for content and instructional strategy |This day begins with a brief discussion about the human body and how equilibrium in |
| |weight is maintained or disrupted. This is an opportunity to get the students to draw|
| |from materials learned during the previous lesson and situate their next activity. |
| |Then the students participate in a structured inquiry activity. The activity is |
| |designed for students who may not have very much exposure to scientific inquiry and |
| |need a highly structured protocol with areas where they can practice some of the |
| |skills necessary for scientific experimentation such as building models, creating |
| |hypotheses, carrying out a protocol, and analyzing data. The purpose of using heart |
| |rate response to exercise for this activity is to get students to think about the |
| |human body as a system where homeostasis is extremely important. The major purpose |
| |for this day is to practice science skills and regain comfort and confidence in |
| |“scientific lingo” while discovering content. Because of the nature of the |
| |experiment, this is a good activity to use to assess student’s experience with |
| |scientific inquiry; I will be able to observe students’ comfort levels with inquiry |
| |skills. |
|4. Evidence of understanding |I will circulate throughout the room while students are doing their data collections |
| |and make sure that they are on track, and answer any questions. This doubles as an |
| |opportunity to make informal observational assessments for each pair of students. |
| |After the students have revised their models, I can make another informal assessment |
| |based on the students’ understanding of how to create and revise models, comparing to |
| |what I observed the initial model to be earlier during rounds. |
|5. Resources |Stopwatches. |
|Day 3: Why does heart rate change after exercise? (75 min.) |
|1. What students are doing |Students will continue with their information gathered during the previous day’s |
| |activity. If any portion of the activity was not completed in the last class period, |
| |there will be time at the beginning of this class to finish up. Each pair will draw |
| |their revised model on the board, and the class will hold a discussion about the |
| |similarities and differences of the classes’ results. When this has been completed, |
| |students will get back into their original group of 4 (from day 1) and discuss the |
| |results of their experiments and brainstorm reasons why they think that the heart rate|
| |may have changed the way it did based on their models. Each group will write their |
| |“best” explanation on an overhead sheet that will be displayed for the class. The |
| |class will then discuss these ideas and come to a consensus as to which are the most |
| |salient. The class will then listen to a mini-lesson on the cardiovascular system and|
| |its role in transporting oxygen and nutrients to working muscles, and will take notes |
| |in their notebooks. |
|2. Objectives |1.1 Students will understand that homeostasis is a state of balance, where the system |
| |(be it an organism, tissue, organ, or cell) responds to changes in the environment |
| |(internal or external) by making adjustments within the system in order to regain that|
| |balance. |
| |3.2 Students will understand how to create and revise a scientific model based on |
| |their hypothesis and data analysis. |
|3. Reasons for content and instructional strategy |The students will present their model to the class by drawing it on the board. I will|
| |lead a class discussion that will involve the students critiquing the presented |
| |models, comparing and contrasting the models, and compiling the class’ ideas into one |
| |class model. The purpose of this strategy is to give students the experience of |
| |sharing their ideas with their peers and to get them to defend their scientific |
| |thinking. Having the students regroup in their small discussion groups to draw |
| |scientific conclusions based on the class model is important in bridging the gap |
| |between the activity, discovering what happened to the heart rate after exercise; and |
| |the scientific explanation for why this phenomenon occurs. It is an important sense |
| |making process, and it directly leads into a “teachable moment” about the |
| |cardiovascular system’s role in delivering oxygen and nutrients to working muscles. |
| |This information is delivered to the students when they have reached an impasse in |
| |their abilities to explain the phenomenon they observed. This also gives the teacher |
| |the opportunity to circle back and directly explain this in terms of homeostasis, |
| |relating back to the first activities the students did, discussing equilibrium. |
|4. Evidence of understanding |The purpose of having the students evaluate all of the models and combine them into |
| |one class model (Phase V- assessment) is for the teacher to have a way of assessing |
| |each group’s work and to assess whether or not the class understands how to build a |
| |simple model. |
| |For homework, students will do a free write explaining why they think humans breathe |
| |deeper and at a faster rate during exercise. This gives the students an opportunity |
| |to take what they have learned about homeostasis in the human body with reference to |
| |heart rate and apply it to a new situation. I will read through the responses to get |
| |a sense for how many students have a true understanding of the concept of homeostasis |
| |in these situations. |
| |Both the free write and the class model will be added to each student’s portfolio. |
|5. Resources |Overhead projector, overhead sheets, overhead pens, notes for mini-lesson on the |
| |cardiovascular system, an overhead of the cardiovascular system for reference. |
|Day 4: Wrap up exercise activity; Chicken egg osmosis! (53 min.) |
|1. What students are doing |In their small groups of 4, students will create a diagram depicting the human body |
| |and the changes that must be made when homeostasis is disrupted (by exercise). |
| |Students must explain what the output of the system is and what the input must be to |
| |regain equilibrium. Students will also explain why the heart rate returns to normal |
| |rate after sufficient rest (30 min.). |
| |Students will format their lab notebook with a table of contents on the first page. |
| |Students will work in pairs for this lab. Students will begin their lab notebook |
| |entry for the “Chicken Egg Lab” (format cover page and make a data table). Each pair |
| |of students will measure initial data for their egg: circumference of egg and mass of |
| |egg. Students will put their egg in a beaker of vinegar and record observations (23 |
| |min.). |
|2. Objectives |2.1 Students will apply the principle of homeostasis to the human body’s responses to |
| |strenuous exercise, including the transport of oxygen and nutrients to the working |
| |muscles of the body. |
| |5.2 Students will learn to safely handle equipment and chemicals in the lab. |
|3. Reasons for content and instructional strategy |The students apply their new knowledge of homeostasis (from the previous day’s lesson)|
| |to their model by diagramming what changes occur in the body relating to homeostatic |
| |balance when it is disrupted during exercise in a poster format. This gives the |
| |students the opportunity to draw meaningful scientific conclusions from their data and|
| |their model, and brings some closure to the activity while leading nicely into the |
| |next activity on osmosis. I am beginning the inquiry activity at this time because it|
| |is going to be a fairly time consuming activity (short periods of time over several |
| |days); and the first step needs to go over the weekend. |
|4. Evidence of understanding |I will collect the group posters, and assess the students understanding of homeostasis|
| |through their representations on the poster. I will take digital images of the |
| |student’s posters that can be filed in the students portfolios as evidence of their |
| |understanding. |
| |I will observe the students during their laboratory exercise to be sure that they |
| |understand how to safely perform the skills necessary in making the preliminary |
| |measurements. I will also carefully monitor the students for the utilization of their|
| |safety goggles when they are working with chemicals in this lab (vinegar). |
|5. Resources |Poster board, markers, raw chicken eggs, strong vinegar, plastic beakers, string, |
| |rulers, Petri dishes, electronic weigh scale, safety goggles, handout for “Chicken egg|
| |lab.” |
|Day 5: How does our body survive environmental temperature changes? (53 min.) |
|1. What students are doing |Students will measure the circumference and mass of their egg and record any |
| |observations. They will replace the vinegar with high concentration salt water, |
| |observe the egg for a few minutes, and then record any new observations. All data and|
| |observations will be recorded in the data table in their lab notebooks. Safety |
| |goggles will be worn at all times during this activity. |
| |In small groups (3 or 4), students will discuss their ideas about the following |
| |prompt: “Why don’t we (as healthy individuals) overheat and get very sick when the |
| |temperature in Kenmore reaches 110°F during a 6-day heat wave in mid-August (assume we|
| |do not have air conditioning)?” They will write their brainstorming ideas down on a |
| |piece of paper that they will bring to the next class. |
|2. Objectives |1.3 Students will understand that temperature regulation in mammals is an example of |
| |homeostatic balance, and be able to explain this phenomenon through this lens. |
| |5.1 Students will learn to work well with their peers through group work. |
|3. Reasons for content and instructional strategy |The laboratory exercise will be ongoing throughout the week, so the beginning of the |
| |class today is dedicated to part of this activity. |
| |The students will participate in more group discussions, utilizing their previous |
| |knowledge from class (and from outside of class) to discuss homeostasis in terms of |
| |temperature regulation. This is another chance for eliciting student ideas. |
|4. Evidence of understanding |I will listen to student discourse during small group discussion to see what their |
| |ideas are and to make sure that they are making the proper connections to prior |
| |knowledge about homeostasis. |
| |Students will fill out a self evaluation on their group work skills for the day which |
| |will be kept in their portfolio. |
|5. Resources |Plastic beakers, string, rulers, Petri dishes, electronic weigh scale, safety goggles,|
| |high concentration salt water. |
|Day 6: Why do I have Goosebumps? Brrr… (75 min.) |
|1. What students are doing |Students will measure the circumference and mass of their egg and record any |
| |observations. They will replace the colored water with fresh water, observe the egg |
| |for a few minutes, and then record any new observations. All data and observations |
| |will be recorded in the data table in their lab notebooks. Safety goggles will be |
| |worn at all times during this activity. |
| |As a continuation of yesterday’s group discussion, the small groups will reconvene and|
| |continue their discussions. As a group, students will come up with a model of what |
| |they believe happens in the body when the environmental temperature is both warmer and|
| |colder than the average human’s core body temperature that aid in survival during |
| |these changes. They will explain this in terms of homeostatic balance. Each student |
| |must have a copy of this initial model. |
| |Students will then listen to a mini-lesson on thermoregulation. Students will take |
| |notes in their notebooks. |
|2. Objectives |1.3 Students will understand that temperature regulation in an endotherm is an example|
| |of homeostatic balance, and be able to explain this phenomenon through this lens. |
| |3.2 Students will understand how to create and revise a scientific model based on |
| |their hypothesis and data analysis. |
|3. Reasons for content and instructional strategy |The laboratory exercise will be ongoing throughout the week, so the beginning of the |
| |class today is dedicated to part of this activity. |
| |Students then have another opportunity to create a model of how they imagine |
| |thermoregulation to work in mammals, utilizing their understanding of homeostasis to |
| |explain this phenomenon. It is another opportunity for students to understand this |
| |principle of balance in a new situation. |
|4. Evidence of understanding |For homework, the students will each revise their original model based on the |
| |information they received in class. Their initial model and their revised model will |
| |be fastened together and added into their portfolio. I will be able to assess their |
| |process of designing and revising a model as well as their conceptual understanding of|
| |thermoregulation from this activity. |
|5. Resources |Plastic beakers, string, rulers, Petri dishes, electronic weigh scale, safety goggles,|
| |fresh water. |
|Day 7: Introducing diffusion (75 min.) |
|1. What students are doing |Students will measure the circumference and mass of their egg and record any |
| |observations. They will replace the high concentration salt water with corn syrup, |
| |observe the egg for a few minutes, and then record any new observations. All data and|
| |observations will be recorded in the data table in their lab notebooks. Safety |
| |goggles will be worn at all times during this activity. |
| |Students will perform a laboratory experiment: Diffusion across a selectively |
| |permeable membrane. In this activity, students will put two different molecules in |
| |dialysis tubing, Riboflavin and Dextran (a complex compound sugar that is labeled with|
| |an attached dye). Students will design a controlled experiment in which they can |
| |determine which molecule will be able to cross the membrane. The experiment will go |
| |on overnight. Safety goggles will be worn at all times during this activity. |
|2. Objectives |2.2 Students will demonstrate understanding of diffusion across a selectively |
| |permeable membrane. |
| |3.1 Students will understand how to create scientifically valid hypotheses. |
|3. Reasons for content and instructional strategy |In order to have a better understanding of what is going on in the chicken egg lab; |
| |students will do a small experiment in which they observe diffusion across a |
| |selectively permeable membrane. I do not intend to make obvious the connections |
| |between the two labs, that should be made by the students in answering questions in |
| |the future days planned for the chicken egg lab. |
| |This mini lab is structured in such a way that the students can have plenty of support|
| |in how to organize their thoughts in designing their experiment (there are specific |
| |steps that they need to follow before “doing the experiment”). This will help |
| |scaffold the students understanding of the scientific process. |
| |All steps will be written in their lab notebooks immediately following the chicken egg|
| |lab, and formatted in the same way. |
|4. Evidence of understanding |The first objective (2.2) really will not be assessed on this day since it is a two |
| |day experiment, but it will be introduced and explored. |
| |I will check student’s hypotheses before they can continue and begin their experiment;|
| |this way I can assess for understanding of how to create a valid, testable hypothesis.|
|5. Resources |Plastic beakers, string, rulers, Petri dishes, electronic weigh scale, safety goggles,|
| |corn syrup, dialysis tubing, Riboflavin, Dextran (dye-labeled), stir bars, stir |
| |plates, plastic transfer pipettes. |
|Day 8: Continuing diffusion … (53 min.) |
|1. What students are doing |Students will measure the circumference and mass of their egg and record any |
| |observations. They will replace the old corn syrup with fresh corn syrup, observe the |
| |egg for a few minutes, and then record any new observations. All data and |
| |observations will be recorded in the data table in their lab notebooks. Safety |
| |goggles will be worn at all times during this activity. |
| |Students will then observe and record information about any changes to their dialysis |
| |tubing experiment. Safety goggles will be worn at all times during this activity. |
| |Then they will write a conclusion for their experiment, addressing whether or not |
| |their hypothesis was correct and why. |
|2. Objectives |2.2 Students will demonstrate understanding of diffusion across a selectively |
| |permeable membrane. |
| |3.3 Students will understand that conclusions must be based solely on the data |
| |collected during experimentation; any claims outside of this data are unsubstantiated.|
|3. Reasons for content and instructional strategy |Students will concentrate on drawing feasible, substantiated conclusions based on the |
| |data they have collected during their diffusion activity. This is going to be good |
| |practice for the final phase of the chicken egg lab that will be done in the next |
| |class period. |
|4. Evidence of understanding |Based on the conclusions written in the students lab write up, I can assess for |
| |understanding of the principle of diffusion. I will also be able to assess their |
| |understanding of objective 3.3 based on this conclusion, if explanations appear that |
| |are outside of the support of the evidence, then I will know that I need to reiterate |
| |the importance of this objective. |
|5. Resources |Plastic beakers, string, rulers, Petri dishes, electronic weigh scale, safety goggles,|
| |corn syrup. |
|Day 9: My own experiment! (53 min.) |
|1. What students are doing |Students will measure the circumference and mass of their egg and record any |
| |observations. Students will deliberate over the findings in their chicken egg lab so |
| |far. They will answer the following question in their lab notebook: “In what liquids |
| |did the egg’s size increase? Decrease? What explanations might you have to explain |
| |this phenomenon?” Students will then design their own experiment. The students will |
| |choose from a variety of liquids provided by the teacher, which they will add to their|
| |chicken egg and observe the changes. First, they must create a hypothesis for what |
| |they think will happen to the egg, and write an explanation in their notebook as to |
| |why it will happen (scientific reasoning based on previous evidence). Then, they may |
| |add the chosen liquid to their egg, and record any observations. All data and |
| |observations will be recorded in the data table in their lab notebooks. Safety |
| |goggles will be worn at all times during this activity. |
|2. Objectives |2.3 Students will demonstrate understanding of the phenomenon of osmosis. |
| |3.1 Students will understand how to create scientifically valid hypotheses. |
|3. Reasons for content and instructional strategy |By this point, students have had an opportunity to observe osmosis in their chicken |
| |egg, and it is reasonable that they might be able to come up with an explanation for |
| |their observations. Based on their evidence, they are at a point where they can |
| |design their own experiment and test their hypothesis regarding a new liquid in their |
| |egg model and what might occur. The students have had some experience in designing |
| |their own experiment (in the diffusion lab), so it is a good time to build on that |
| |skill. |
|4. Evidence of understanding |I will check students’ hypotheses to make sure that they are valid and testable before|
| |they try to do their experiment. |
| |I will listen to student dialogue to get an idea of the class’ understanding of |
| |osmosis. |
|5. Resources |Plastic beakers, string, rulers, Petri dishes, electronic weigh scale, safety goggles,|
| |a variety of liquids (such as vegetable oil, soy sauce, water with food coloring, |
| |etc.). |
|Day 10: Wrap-up “Chicken egg lab” (75 min.) |
|1. What students are doing |Students will measure the circumference and mass of their egg and record any |
| |observations. All data and observations will be recorded in the data table in their |
| |lab notebooks. Safety goggles will be worn at all times during this activity. Once |
| |all data has been collected, students will create a graph of their data (egg’s |
| |circumference vs. mass) to paste into their lab notebooks. Then they will answer the |
| |following questions in a conclusions section: |
| |1.) “Was your hypothesis correct? Describe why your experiment either proved or |
| |disproved your hypothesis. Use interpretations of your graph as evidence to support |
| |your argument.” |
| |2.) “Based on your knowledge of the movement of molecules across the chicken membrane,|
| |can you explain what might happen to an animal cell that is placed in a high |
| |concentration of salt water? Relate your explanation to your findings. Why might |
| |this be an important process for cell survival?” |
|2. Objectives |2.3 Students will demonstrate understanding of the phenomenon of osmosis. |
| |3.3 Students will understand that conclusions must be based solely on the data |
| |collected during experimentation; any claims outside of this data are unsubstantiated.|
|3. Reasons for content and instructional strategy |This lesson is gives an opportunity for students to bring everything together and have|
| |a “sense-making” session with their lab partner. The questions have been designed to |
| |get the kids thinking about how to apply this knowledge to a new situation (relate the|
| |egg to an animal cell). This is important because the unit following this homeostasis|
| |unit will be on cell structure and function, so this is a good segue into that unit. |
| |I again reiterate the importance of drawing conclusions solely based on evidence |
| |collected during the activity. This is essential to good science and I personally |
| |find it to be an important aspect of doing laboratory science that I would like to |
| |stress to the students regularly. |
|4. Evidence of understanding |When the lab write-ups are complete, I will collect the lab notebooks and grade both |
| |the diffusion lab and the osmosis lab. I will be able to assess for student |
| |understanding of both objectives for the day. |
|5. Resources |Plastic beakers, string, rulers, Petri dishes, electronic weigh scale, safety goggles,|
| |graphing paper, colored pencils. |
|Day 11: What is osmosis? (75 min.) |
|1. What students are doing |Students will listen to a mini-lesson on the phenomenon of osmosis in a cell. |
| |Students will do a mini-activity to support their understanding of osmosis. They will|
| |create a wet mount of a piece of onion skin using distilled water, and observe it |
| |under the microscope. Then they will replace the water with a 10% NaCl solution and |
| |observe any changes. Finally, they will wash out the salt by adding several |
| |“irrigations” of distilled water and observe any changes. They should record all |
| |observations in their lab notebooks, and come up with a rule that explains their |
| |observations. Then students will listen to another mini-lesson about the differences |
| |between osmosis in a plant cell and in an animal cell. |
|2. Objectives |2.4 Students will know the difference between osmosis in a plant and animal cell. |
| |4.2 Students will be able to explain osmosis by referring to examples in their |
| |everyday life. |
|3. Reasons for content and instructional strategy |This class period is a prime opportunity for some “just in time teaching” about |
| |osmosis in cells. We have not had much of a chance to relate to cells up to this |
| |point, so it is a good opportunity to get the students thinking on this level. I |
| |chose a “guided inquiry” activity for this lesson as well, to give the students an |
| |opportunity to see osmosis occur in a plant cell, and build from their understanding |
| |of osmosis in the chicken egg. |
|4. Evidence of understanding |For homework, the students will answer the following questions: |
| |1. “If a lawn is fertilized and it does not rain, the grass often dies. Why?” |
| |2. “Roads are sometimes salted to melt ice. What does this salting do to the plants |
| |along the roadside? Why?” |
| |3. “(For extra credit) – The Paramecium, a single celled protest (no cell wall), lives|
| |in pond water. Water tends to enter the cell through osmosis. What kind of structure|
| |would need to exist in the cell in order to osmoregulate (control water balance)?” |
|5. Resources |Onion, distilled water, 10% NaCl solution, paper toweling, glass slides, cover slips, |
| |eyedroppers, dissecting microscopes (Objective 10X), overhead projector, overheads of |
| |plant and animal cells. |
|Day 12/13: Wrap-up of homeostasis! (53 min.) |
|1. What students are doing |Students will work on culminating product. In pairs, students will answer the |
| |essential question posed at the beginning of the unit, “How does your body physically |
| |respond to strenuous exercise?” They will describe (in detail) what is happening at |
| |an organ/tissue level within the organism, and what is happening at the cellular |
| |level. They will have two days to work in class on this project, and will have the |
| |weekend to do any work together outside of class. The final product will be a poster.|
| |Students should use the information they have collected in their lab notebooks as well|
| |as in their portfolios to aid in this task. They may also ask for the teacher’s help |
| |in understanding more details about the system that they have chosen. |
|2. Objectives |1.1 Students will understand that homeostasis is a state of balance, where the system |
| |(be it an organism, tissue, organ, or cell) responds to changes in the environment |
| |(internal or external) by making adjustments within the system in order to regain that|
| |balance. |
| |5.1 Students will learn to work well with their peers through group work. |
|3. Reasons for content and instructional strategy |This culminating project incorporates many important aspects of “doing science”: |
| |working with peers, integrating conceptual understanding of information gathered |
| |through experimentation, creating a poster, defending your ideas about a particular |
| |topic to your peers, and asking thoughtful scientific questions. I integrated all of |
| |these aspects of good science in an authentic task so that students have experience |
| |early in the year with assembling conceptual information in a valuable way. |
|4. Evidence of understanding |The posters will be graded on content understanding. Students will fill out a self |
| |evaluation on their group work skills for the day which will be kept in their |
| |portfolio. |
|5. Resources |Poster board, colored pencils, crayons, markers, glue, scissors, paper. |
|Day 14: Presentations! (75 min.) |
|1. What students are doing |Students will present their posters. One of the pair of students will stand by |
| |his/her poster to offer explanation and answer any questions posed by the visitors. |
| |The other of the pair will walk around and visit other posters, and ask questions |
| |about their work. After 30 minutes, they switch roles. |
|2. Objectives |5.3 Students will express ideas through oral and written expression (EALR 2.1.5). |
| |5.4 Students will defend their scientific conclusions or arguments (EALR 2.1.5). |
|3. Reasons for content and instructional strategy |I believe that this is a fantastic way to get kids to communicate with their peers |
| |about science. It forces them to explain their thinking to other students, to defend |
| |their conclusions based on evaluation of data and understanding of the concepts of the|
| |unit. It is good practice for them to get ready for the unit exam. |
|4. Evidence of understanding |Students will fill out peer assessments which include how well the presenter of the |
| |poster answered questions, and I will go around the room and ask clarifying questions |
| |of the presenters as well. I will be able to assess how well the student expresses |
| |him/herself orally, and how well they understand the concepts of the unit by their |
| |success in defending their arguments. |
|5. Resources |Tape, thumbtacks. |
Unit ends with a culminating unit exam; traditional items; 75 min. class period.
Erin M. Flynn
Homeostasis Unit: Pre-Planning Products
10th Grade Biology
March 24, 2004
Unit Pre-planning Products
1. Topic/Concept of Unit
EALRs relevant to topic:
1.2.1: Analyze systems, including inputs and outputs.
This will be covered in the discussions surrounding homeostasis and temperature regulation in animals.
1.3.7: Explain how organisms can sustain life by obtaining, transporting, transforming, releasing, and eliminating matter and energy.
This will be essential in the discovery of both homeostasis within an animal and at the cellular level.
2.1.2: Design, conduct, and evaluate systematic and complex scientific investigations, using appropriate technology, multiple measures, and safe approaches.
Students will perform guided discovery activity as a performance assessment for osmosis in a chicken egg; activity will begin highly structured and will lead to the eventual design of a small portion of the experiment by the students.
2.1.3: Formulate and revise scientific explanations and models using logic and evidence; recognize and analyze alternative explanations and predictions.
As part of the osmosis activity, students will be asked to revisit hypotheses and either support or refute based on data collected and observations made.
2.1.5: Research, interpret and defend scientific investigations, conclusions, or arguments; use data, logic, and analytic thinking as investigative tools; express ideas through oral, written, and mathematical expression.
Claims made by the students will need to be supported by evidence gathered during experimentation. Formal lab write-ups will be done.
3.1.3: Compare, contrast, and critique divergent results from scientific investigations based on scientific arguments and explanations.
Students will share a summary of their results with the class and be able to discuss divergent results in a scientific manner (arguments based on evidence.
Where does this fall in the Atlas of Scientific Literacy?
The topic of homeostasis falls into the Atlas of Scientific Literacy under a couple of different webs. The main (or most relevant) web for osmosis and diffusion falls under “Cells: Cell Functions.” Within this map, there is a section that states, “Within cells, many of the basic functions of organisms – such as extracting energy from food and getting rid of waste – are carried out. The way in which cells function is similar in all living organisms.” This can be directly related to regulation in the internal systems of an animal.
2. Rationale Paragraph
The topic of the unit I will be preparing is homeostasis, which is an extremely important topic in biology. Homeostasis falls into the Atlas of Scientific Literacy under a couple of different webs. The main (or most relevant) web for osmosis and diffusion falls under “Cells: Cell Functions.” Within this map, there is a section that states, “Within cells, many of the basic functions of organisms – such as extracting energy from food and getting rid of waste – are carried out. The way in which cells function is similar in all living organisms.” This can be directly related to regulation in the internal systems of an animal. Another reason that this topic is essential is that it is found in the Washington State EALRs, #1.3.7: “Explain how organisms can sustain life by obtaining, transporting, transforming, releasing, and eliminating matter and energy.” This is the crux of homeostasis within an organism and directly parallels the Atlas findings (above). The homeostasis unit will be one of the first units of the school year. I intend it to begin with the regulation of an animal’s internal environment on a systems level, such as temperature regulation; and end with cellular regulation such as osmoregulation, to lead into future lessons on cellular structure and functions. I have been trying to find a way to begin the school year with a relatively simple concept (balance and regulation) that can immediately engage students by the sheer nature of the obvious necessity of balance in life. I think that it would be easier to get kids to begin to understand some complex topics in biology if I can give them a solid understanding of the importance of balance and regulation in organisms and cells. From there, they could see the running theme in the unit on ecosystems, more specifically in predator/prey relationships and population ecology; in the conservation of energy, and many other big ideas in science that directly relate to balance. The study of regulation in the internal environment of an animal can lead to the study of regulation in cells, which can lead to more detailed studies of cellular structures and their related functions, of the similarities of organ systems among various organisms, etc. This unit is primarily a way to get kids thinking about science, to give them a “lead-in” to other topics of importance in the study of biology. Understanding homeostasis will allow for students to understand the principle of balance that s/he witnesses in his/her everyday life. For example, the studies of the checks and balances in the United States government may be clearer after understanding the principles governing the maintenance of balance on a biological level. The student will have a better grasp of how businesses become successful, the flow of money, of personnel, of materials and products. S/he will understand why it is important for our country to invest time and money into generating a substitute for oil that is inexpensive and simple to create. These three situations all relate to the general idea of balance, of a simple give and take necessary to keep a system stable and functioning well.
3. Concept Map of Topic (minimum 20 nodes) (see Powerpoint file)
4. Critical Attributes
1. Homeostasis is achieved through a variety of mechanisms that auto-correct for small differences in their internal and/or external environment(s).
2. The exchange of energy and materials with the environment is balanced by homeostasis.
3. Single-celled organisms have regulatory systems in place that permit them to survive extremely harsh osmotic environments.
4. An animal’s metabolism can change in response to a variety of stimuli, keeping the animal stable (body mass, temperature, etc.).
5. The circulatory system of large animals (and blood in particular) is an extremely important player in most homeostatic processes in the animal.
5. Description of Culminating Project or Product
The culminating product for this unit will be a poster project in which the students describe in detail one of the many aspects of the essential question, “How does your body physically respond to strenuous exercise?” Students will work in pairs to produce a poster that provides examples and explanations of homeostasis at two levels: in the whole organism, with respect to homeostatic balance regulated by an organ/tissue system; and in a cell. Students must produce a graphic representation of their examples for each of the levels of homeostasis involved in this poster summary. They may draw pictures, use magazine clippings, download appropriate pictures from the internet, etc. Under each diagram, there must be a typed “figure legend” pasted below, explaining in detail what the student is depicting and how it represents homeostasis at that level. The students may choose to describe what is happening in a cell within the context of their organ/tissue example; or it could be an entirely different unrelated example.
The descriptive text (for each of the examples) should include the following:
• What the imbalance is in the example and what caused it
• What adjustments must be made to return to a homeostatic balance
• Whether or not energy is needed to reset the system to a balance
• One must include the concept of osmosis/diffusion
• One must include a discussion of the influence of metabolism on this system
• The tissue/organ system example must be chosen from the following list (students are expected to do more in depth research on their specific system and explain it’s role in maintaining homeostasis in an organism):
o Circulatory system
o Digestive system
o Respiratory system
• Is there a known disorder/illness in humans that disrupts the normal processes that should occur in the system and situation that you chose? Explain what happens in this situation and what doctors can do to help the patient maintain a homeostatic balance.
The posters will be presented to the class, in a professional poster session format. This will be organized in such a way that all posters will be on display, and one of the “authors” of the poster will stand by his/her poster to offer explanation and answer any questions of the audience. The other “author” is free to walk around and look at the other students’ work. After 30 minutes, the pair will switch roles. As the students walk around the room looking at other people’s posters, they will also be responsible for completing a peer assessment form for each poster that they view. The teacher will assign him/her to view 1/3 of the class posters; if s/he has extra time s/he should feel free to visit the rest of the posters of his/her choice. Students will peer assess on how neat and clear the diagrams are, how well the presenter answered questions about the poster (students will receive credit towards their own poster project for asking one question of each presenter and documenting both the question and the answer), and how much effort they think went into the project. These peer assessments are mainly to guide the students to think critically about viewing peers’ work, which they will need to be able to do in the field of scientific research, and to stimulate scientific discourse between the audience and the presenter, another authentic task that is essential to a good scientific poster presentation.
6. Essential Questions
1. Why don’t we (as healthy individuals) overheat and get very sick when the temperature in Kenmore reaches 110°F during a 6-day heat wave in mid-August (assume we do not have air conditioning)?
2. How does your body physically respond to strenuous exercise? In other words, what exactly is happening inside your body when you are running around while participating in your favorite sport?
7. Backward Planning Sequence
1. Description of maintenance of homeostatic balance.
2. What kinds of changes occur in the body that causes an imbalance and disrupts homeostasis.
3. What organ/tissue systems are involved in the body’s response.
4. How the body responds to these disruptions.
5. What the normal function of this organ system is.
6. How the system is regulated.
7. If the system affects metabolism, or vice versa.
8. What types of materials are transported in this system.
9. How the materials are transported to and from the cells in this system.
10. Whether or not osmoregulation is important to homeostasis in this situation.
11. How osmosis/diffusion occur.
12. How water balance is maintained in the body and in the cell.
13. How to artificially manipulate a system that is flawed due to a disorder/illness in order to maintain homeostasis.
14. How temperature regulation occurs.
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