TEKS Lesson Plan/Unit Plan



Focus Plan

Texarkana Independent School District

|GRADING PERIOD: |2nd 6 Weeks |PLAN CODE: | |

|Teacher: |Winton |Course/subject: |Mathematics |

|Grade(s): |7 |Time allotted for instruction: |1 hour |

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|Title: |Fun with Circles! |

|Lesson TOPIC: |Circumference of a Circle |

| | |

|TAKS Objective: |Objective 3: |

| |The student will demonstrate an understanding of geometry and spatial reasoning. |

|FoCUS TEKS and Student Expectation: |(4) Patterns, relationships, and algebraic thinking. The student represents a relationship in |

| |numerical, geometric, verbal, and symbolic form. The student is expected to: |

| |(A) generate formulas involving conversions, perimeter, area, circumference, volume, and scaling |

|Supporting TEKS and Student Expectations: |(15) Underlying processes and mathematical tools. The student uses logical reasoning to make |

| |conjectures and verify conclusions. The student is expected to: |

| |(B) validate his/her conclusions using mathematical properties and relationships |

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|Concepts |Enduring Understandings/Generalizations/Principles |

| |The student will understand that |

|Circle |A circle is a closed curve with all points on the curve an equal distance from a given point called the|

| |center of the circle. |

|Diameter |The diameter of a circle is the line segment that passes through the center, with endpoints on the |

| |circle. |

|Radius |The radius of a circle is the line segment with one endpoint at the center of the circle and the other |

| |endpoint on the circle. |

|Circumference |The circumference of a circle is the distance around it. |

| |C = 2ér |

| | |

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[pic]I. Sequence of Activities (Instructional Strategies)

A. Focus/connections

Items needed:

• Compass for each child

• Copy of Circle worksheet for each child

• Rulers

• String or yarn

• Tin Cans of various sizes

• Index cards with circumference formula (for students requiring modifications)

Prior to students entering the classroom, teacher will place a large circle on the board. Teacher will have each student (using a compass) construct a circle on their Circle worksheet. Emphasize that the circle can be any size as long as it fits on the paper given. Next have them put a dot in the center of the circle and draw a line from the dot to an endpoint of the circle. Have students label this the radius. Teacher will model, using the circle on the board.

B. Instructional activities

(demonstrations, lectures, examples, hands-on experiences, role play, active learning experience, art, music, modeling, discussion, reading, listening, viewing, etc.)

The teacher will explain the meaning of the radius to the students. Have each student measure the radius of their circle and record the results on their paper. Next explain what a diameter of a circle is and have the students draw the diameter of their circle. Have them measure the length of the diameter and compare this measurement to the radius. Ask, “What pattern do you see?” Emphasize that the diameter of a circle can be calculated by multiplying the radius by two. Also show that the radius of a circle can be calculated by dividing the diameter by two. Give your students the following scenario, “The radius of a circle is 12 ft. What is the diameter?” Now hold up a tin can. Ask for suggestions on how to find the distance around the can. Tell your students that the distance around the can is called the circumference of the circle. Wrap a piece of string around the outside of the top of the can and measure the length of the string needed to get around the whole top. Next put the formula for calculating the circumference of a circle on the board (C = 2ér). Explain that pi (é) is approximately 3.14.

B. Guided activity or strategy

Have students get in groups of 2 – 3. Give each group a tin can and a piece of string. Have them calculate the circumference of the can using the formula on the board. Next have them use a piece of string to wrap around the top of their can. Students will then use a ruler to measure the length of string needed. Have the group compare the two answers. Reinforce that either method will find the circumference of the can.

D. Accommodations/modifications

Students requiring modifications will be paired with a peer to complete the group activity working with circumference.

E. Enrichment

II. STUDENT PERFORMANCE

A. Description

Students will complete the Circumference worksheet individually.

B. Accommodations/modifications

C. Enrichment

iii. Assessment of Activities

A. Description

Individual grades may be taken on the Circumference worksheet.

B. Rubrics/grading criteria

Grades may be taken based on the Circumference worksheet answer key/grading rubric

C. Accommodations/modifications

Students requiring accommodations may be given an index card with the circumference formula to use while completing the Circumference worksheet.

D. Enrichment

E. Sample discussion questions

• Why would we need to know the circumference of a circle?

• What is the difference between the radius and circumference of a circle?

IV. TAKS Preparation

A. Transition to TAKS context

The teacher will lead the students in a discussion of how circumference problems my look in test format by placing the TAKS questions below on the board/overhead.

B. Sample TAKS questions

1. Mrs. Penn has a circular tablecloth with a circumference of 29 feet. Which expression could be used to find the radius of the tablecloth?

F. 29 - 2é

G. 29/2é

H. 29/é

J. 29 + 2é

2. Luis is in charge of making props for a school play. He needs to make a large circular wooden clock that measures about 6 feet in circumference. Which equation can he use to find r, the radius of the clock?

A. r = 6/é

B. r = 12/é

C. r = 6/2é

D. r = 12/2é

V. Key Vocabulary

Circle, Diameter, Radius, Circumference

VI. Resources

A. Textbook

Math Advantage, Middle School II

Chapter 14: Ratios and Rates

• Finding Pi, pp. 289

Chapter 23: Experiments with Probability

• Geometric Probability, pp. 454–455

Chapter 24: Measuring Length and Area

• Using a Formula to Find the Area, pp. 476-478

B. Supplementary materials

• Circle worksheet

• Circumference worksheet

• Circumference worksheet answer key/grading rubric

C. Technology

For additional practice, students may be taken to the following websites:





VII. follow up activities

(reteaching, cross-curricular support, technology activities, next lesson in sequence, etc.)

• This lesson is a good introduction to show the relationship between the diameter and the circumference. The student should discover that the circumference of a circle is about three times (pi) the length of the diameter.

VIII. Teacher Notes

Another way to make learning about circumference a little bit more entertaining is to go out and purchase bubbles for your class. After students learn the formula and reasoning behind the circumference of a circle, then head outside. While there, give each group of students a bottle of bubbles and have them blow away! As the bubbles are floating back to the ground, have students catch them on construction paper. The paper soaks up the burst bubble and forms a circle. Then students can measure the diameter and compute the circumference of that bubble circle.

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