Chemistry Department’s iGCSE Assessment Guidebook (DRAFT)



Chemistry Department’s iGCSE Assessment Guidebook (DRAFT)Basically there are these main standardised ways we assess students achievement End of topic tests (using only questions from CIE past exam papers)Practical write up (based on the IBDesignData collection and processingConclusion and evaluationEssays, using a rubric based on the extended essay rubric Mini-symposia focusing on ToK, using a rubric based on the one issued for the ToK presentationOther less formal systems like directed questioning in class, class participation, manipulative skills during practicals, ability to work within a team in practicals, verbal communication skills in classFor the practical write ups and the essays the students should be given a chance to improve their work based on your feedback so they learn more deeply where they are going wrong and how they can improve to produce the best work possible. It is therefore very useful to see these excercises very much as formative assessment rather than summative, if they get it wrong, you should tell them and then they should be given the opportunity to fix it. Design (D)D1- Defining the problemD1aYou have provided a focused research question of what you intend to do./2D1bYou have given a qualitative hypothesis and justified it with quantitative scientific reasoning (using a calculation or chemical equation)./2D1cYou attempt to explain the scientific reasoning behind the most important variables you are going to control./2D2 - Selecting variablesD2aStates the independent variable (the one you change)/1D2bStates the dependant variable (the one you measure)/1D2cStates the controlled variable(s) (the one(s) that must be kept constant)/2D3- Developing a method for collection of dataD3aSelects and names appropriate apparatus and materials needed/2D3bDesigns a method that allows for the effective control of the variables/2D3cDesigns a method that allows for the collection of sufficient relevant data/2Total marks/16Data Collection and Processing (DCP)DCP1Collect and organize raw dataDCP1aYou have successfully recorded all raw data (qualitative and/or quantitative)./2DCP1bYou have presented the raw data in a complete and clear manner./2DCP1cYou have always used the correct headings, units and decimal places for you measurements. All of your measurements are recorded with the correct amount of precision. /2DCP2Processing raw dataDCP2aYou have always made the correct calculations with the raw data./2DCP2bYou have always used the correct units and significant figures in your solutions to calculations./2DCP2cYou have extracted the relevant data from the graph. Where a graph is not drawn (e.g. in titrations), you have processed and presented all of the data correctly in a single table with the correct number of significant figures./2DCP3Presenting processed dataDCP3aYou have the processed data appropriately (correct choice of graph, bar chart etc.). Where further calculations are required (e.g. titrations), you have selected and shown the correct formulas needed for the calculation./2DCP3bWhen a graph is needed you have chosen an appropriate scale and plotted points/displayed processed data correctly/added trend line and given an equation for trend line. Where further calculations are required (e.g. titrations) you have always clearly presented a sample calculation. /2DCP3cIf you needed to draw a graph you have used correct labels, units and line of best fit drawn (if graph chosen). Where further calculations are required (e.g. titrations), the correct answer is presented with correct units./2Total marks/18Manipulative Skills (MS)MS1- Instruction MS1aYou have followed VERBAL instructions/2MS1bYou have followed WRITTEN instructions/2MS1cYou are aware of all instructions about HEALTH & SAFETY/2MS2 - TechniqueMS2aYou have completed the practical is a sensible way/2MS2bYou have completed the practical in a safe way/2MS3- TeamworkD3aYou have made sure everyone in the group has done a fair amount of work/2D3bYou have worked effectively and efficiently in your group /2Total marks/14iGCSE Chemistry Literature Review and Essay Marking SchemeThere are two categories, relating to either Chemistry or to Scientific writing. Each of these different skills can be awarded a Complete (2/2) a Partially complete (1/2) or a Not at all (0/2). In exceptional circumstances the teacher can award a Distinction (3/2) for a particular category, which means it is possible to get more than 100% on these essays!Usually only one category (either 1, chemistry or 2, scientific writing) will be assessed for a given piece of work at any one time (a merit to the first student to spot this), but your use of English will almost always be assessed for every essay. Demonstrating an Understanding of Chemistry (UC)KnowledgeDescribes, states or lists relevant information relating to the topic covered by the title.Understanding Relates the information they have given to a larger idea and uses their understanding of chemistry to EXPLAIN most or all of the information they have provided.Analysis/ConclusionUses the information that they have provided to identify or explain any trends or larger ideas that this information supports.Syllabus/subject relevanceDoes not include irrelevant material and in addition, clearly demonstrates an awareness of the topics relationship to chemistry, e.g. by including correct and relevant chemical equations or by drawing appropriate and labeled diagrams. Correct word countStays within 20% of the word limit, or if you go over, only includes ideas which are essential to the argument and does not go over by too much. Most of the highest scoring essays will be within the word limit. Demonstrating an understanding of good Scientific Writing (SciW)ResearchUses three or more sources of information and provides a complete bibliography.DepthThe essay is to an appropriate depth considering the word limit; it EXPLAINS one particular idea very well, rather than listing just lots of related but different ideas. Insight and originality Choses an unusual or interesting topic to base the essay around, or uses an unusual and interesting approach to their essay. FlairDemonstrates a thorough understanding of the subject that goes well beyond the syllabus and whilst exploring larger ideas, is obviously aware of the syllabus. Tone Uses the correct tone for a scientific essay. Assumes the reader understands the basics of chemistry, e.g. elements and electrons (has iGCSE knowledge), but explains any vocabulary beyond that. Correct word count Stays within 20% of the word limit, or if you go over, only includes ideas which are essential to the argument and does not go over by too much. Most of the highest scoring essays will be within the word limit. Demonstrating an understanding of good EnglishYou will, in addition to either of the assessment categories above also be assessed on your English, each of these can be either, Complete (1/1) or Not at all (0/1). A merit to the first student to spot this.Your typical essay then can either be out of 13 marks for category 1 or 15 marks for category 2. Sometimes you will be required to write a longer essay that covers both categories and so will be out of 28 marks. Use of correct vocabulary Vocabulary, especially keywords, are correctly used and defined where necessaryUse of correct grammarUses grammar correctlyFlow of ideas Good use of punctuation and the essay flows well, with a recognizable beginning, middle and end. Repetition of synonyms is avoided and there is a comfortable feel to the style of language used (i.e. magniloquence is avoided)Checking Notes in Exercise BooksNot at all0/2Partially complete1/2Complete2/2Exceptional3/2Neat and tidyClear writingFull notesDates?Titles?All work stuck into the bookTotal Score:/12Score0-45-89-12Above 12Possible AtL on report4321Checking Notes in Exercise BooksNot at all0/2Partially complete1/2Complete2/2Exceptional3/2Neat and tidyClear writingFull notesDates?Titles?All work stuck into the bookTotal Score:/12Score0-45-89-12Above 12Possible AtL on report4321Checking Notes in Exercise BooksNot at all0/2Partially complete1/2Complete2/2Exceptional3/2Neat and tidyClear writingFull notesDates?Titles?All work stuck into the bookTotal Score:/12Score0-45-89-12Above 12Possible AtL on report4321Checking Notes in TOPIC BooksNot at all0/2Partially complete1/2Complete2/2Exceptional3/2Clear and legible (can you read it?) writingNotes and highlighting of important pointsKeywords completed?All questions answeredSome questions answeredVery few questions answeredNo questions answeredSome evidence of extra reading or going beyond the syllabus?Total Score:/12Score0-45-89-12Above 12Possible AtL on report4321Checking Notes in Exercise BooksNot at all0/2Partially complete1/2Complete2/2Exceptional3/2Neat and tidyClear writingFull notesDates?Titles?All work stuck into the bookTotal Score:/12Score0-45-89-12Above 12Possible AtL on report4321Checking Notes in Exercise BooksNot at all0/2Partially complete1/2Complete2/2Exceptional3/2Neat and tidyClear writingFull notesDates?Titles?All work stuck into the bookTotal Score:/12Score0-45-89-12Above 12Possible AtL on report4321Presentation Rubric (Adapted from ToK)A Identification of knowledge issueDid the presentation identify a relevant knowledge issue involved, implicit or embedded in a real-life situation?DescriptorAchievement levelLevel 1 was not achieved.0The presentation referred to a knowledge issue but it was irrelevant to the real-life situationunder consideration.1–2The presentation identified a knowledge issue that was in some ways relevant to the real-life situationunder consideration.3–4The presentation identified a knowledge issue that was clearly relevant to the real-life situationunder consideration.5B Treatment of knowledge issuesDid the presentation show a good understanding of knowledge issues, in the context of the real-life situation?DescriptorAchievement levelLevel 1 was not achieved.0The presentation showed some understanding of knowledge issues.1–2The presentation showed an adequate understanding of knowledge issues3–4The presentation showed a good understanding of knowledge issues.5C Knower's perspectiveDid the presentation, particularly in the use of arguments and examples, show an individual approach and demonstrate the significance of the topic?DescriptorAchievement levelLevel 1 was not achieved.0The presentation, in its use of arguments and examples or otherwise, showed limited personalinvolvement and did not demonstrate the significance of the topic.1–2The presentation, in its use of arguments and examples or otherwise, showed some personalinvolvement and adequately demonstrated the significance of the topic.3–4The presentation, in its distinctively personal use of arguments and examples or otherwise, showedclear personal involvement and fully demonstrated the significance of the topic.5D ConnectionsDid the presentation give a balanced account of how the topic could be approached from different perspectives?Did the presentation show how the positions taken on the knowledge issues would have implications in related areas?In awarding the higher achievement levels, the emphasis should be more on the quality of the consideration of connections than on the quantity of connections mentioned.DescriptorAchievement levelLevel 1 was not achieved.0The presentation explored at least two different perspectives to some extent.1–2The presentation gave a satisfactory account of how the question could be approached from different perspectives, and began to explore their similarities and differences.3–4The presentation gave a clear account of how the question could be approached from differentperspectives and considered their implications in related areas.5iG Rubric Creating Exam QuestionsStandard format of task:5 multiple choice marks only assessing the “Core” syllabus material (Paper 1)10 marks attached to longer answer questions also assessing the “Supplement” material and including at least one three or four mark question (Paper 3)5 marks given for questions relating to experimental techniques (Paper 6)Essential QuestionsQuestion style -2 marks2All of the questions are of the same style as you would find in a real exam1Some of the questions are in the wrong style e.g. like true/false questions0All of the questions are in the wrong styleLevel of challenge -2 marks2All of the questions are set to an appropriate level of challenge1There is an inappropriate level of challenge to be used by iGCSE0The level of challenge is totally inappropriateUse of Command words – 2 marks2Command words used consistently and appropriately for all questions1Some inappropriate use of command words 0Command words totally missing or consistently used inappropriately Clarity of task – 2 marks2The questions use precise language and it is obvious what you are supposed to do1There is some degree of ambiguity in in the language used so that it is not always obvious what is being asked.0It I s really unclear what is needed to do to answer the question successfullyBreadth of syllabus coverage – 2 Marks2There is an excellent coverage of the syllabus1Some important aspects of the syllabus have been missed out Essential Mark SchemeMark scheme styleAppropriate number of marksMarks linked to the appropriate gradePaper specific criteriaPaper 1Right number of answersAppropriate style of answersPaper 3Calculations are correctChemical equations are appropriatePaper 6Graph question allows an appropriate curveTables appropriate display appropriate trendEssay question Exemplar practical write up: Design (D)Task: Design an experiment in 300 words to investigate salt solutions and temperature. Design (D)1a)Research Question: Investigating the effect salt (NaCl) concentration in mol dm-3 has on the boiling and freezing point measured in oC of a solution1b)Hypothesis: Adding salt will reduce the freezing point but increase the boiling pointNaCl (s) + H2O (l)NaCl(aq)Solutions are mixtures of a solvent, water, and a solute, NaCl. Impure substances like solutions have different fixed points to pure substances because the solute makes bonds with the solvent molecules which makes it more difficult to free them (boil). Also the solute interferes with the freezing process, so the liquid stays liquid at lower temperatures. 2a)Independent variable: Salt (NaCl) concentration (0.0, 0.2, 0.4, 0.6, 0.6 & 1.0 mol dm-3)2b)Dependent Variable: Temperature of the melting and boiling points, oC1c &2 c)Controlled variables: Volume of solution, type of water (used distilled), type of heater (use an electric heater), type of container (250cm3 glass beaker), kind of thermometer3a, 3b & 3c)MethodAdd a thermometer that goes up to 200oC to 100 cm3 of a salt concentration heat with an electric heater set to 200oC. Heat each solution and measure the temperature when it boils.To another 100cm3 of salt solution with the same concentration, cool the solution with ice and measure the temperature with the thermometer when it freezes.Repeat 2 times for the same salt concentration.Repeat steps 1 to 4 for each different salt concentration.Word count: 231Score: 16/16 This is a method for a very simple design experiment, you are essentially just heating and cooling a liquid, so there are not that many variables that need to be controlled. A more complicated experiment, like finding out the amount of energy contained in different fuels, would have much more variables, which would mean the method would need to be much longer in order to effectively control all of those variables, so it would be much harder to get full marks for that design.iG Exemplar DCP MgO Task: Write a 300 word lab report for the Data Collection and Processing skill for the investigation of mass change during the burning of magnesium Data Collection and Processing ExemplarWhen the DCP skill is being assessed you get no marks for providing a method, which is assessed by the Design (D) skill, nor are there any marks for a Conclusion and Evaluation, which is assessed by the CE skill. 1 – Collect and organise raw dataRecord all raw data (qualitative and/or quantitative) /2Presents raw data clearly /2Uses correct headings, units and significant figures. /22 – Processing raw dataMakes the correct calculations on the raw data /2Pays attention to units, significant figures and decimal places in final answer. /2Extracts relevant data from the graph if drawn (intercept, gradient etc.) /23 – Presenting processed dataPresents the processed data appropriately (correct choice of graph, bar chart etc.) /2Chooses an appropriate scale and plots points/displays processed data correctly/adds trendline and gives equation for trendline /2Uses correct labels, units and line of best fit drawn (if graph chosen) /2Total marks available: 18Results table (1a,1b and 1c):5676900387985005676900260350.080.04000.080.04Calculations (2a and 2b)Working out the empirical formula for magnesium oxide:According to the graph, the gradient shows that 1.56g of magnesium oxide is made for every 1g of Mg. Converting this into moles we see that in 1.00g of Mg we have 1.00/24.0 =0.0417 moles of Mg.Of that 1.56g of magnesium oxide, 1.00 g is Mg, so 0.560g is oxygen, or 0.560/16.0=0.035 moles of oxygen.The ratio therefore for magnesium to oxygen (the empirical formula for the compound we made) is:0.0350/0.0350 to 0.0417/0.0350or 1.000 : 0.840Rounding we get: 1:1 of Mg:OEmpirical formula is MgOGraph (2c, 3a,3b and 3c)18/18 (full marks)Comments Results tableAll measured values to the same number of decimal places for each column (which is the number of decimal places, or accuracy, of the equipment). Each column has clear title and units and they are given using the forward slash “/”: e.g. /g, or /s or /cm3 etc.At least 5 different data points for the independent variable present.GraphDrawn in pencil (and after this has been handed in kept in a safe place) – Easy corrections during this write up, as well as after feedback has been given are still possible because of this!X axis = Independent variable (the thing that you can control).Y axis = The dependent variable (the thing that changes as a result of how you have changed the independent variable).The gradient, and how it was worked out, clearly shown on the graph.Anomalous outlier (point that doesn’t fit the pattern) highlighted and ignored.Photo of the graph (applies to all photos of hand-drawn diagrams, results tables etc)You must take a photo that clearly shows your graph. If it can’t be read than you can’t get credit for it!Taken from above (so the lines of the graph paper are parallel to the edges of the photo), in good lighting. Handwriting larger than usual and clearer than usual to overcome any problems created when it is photographed. High resolution photo, displayed in the right orientation in a word document and of a good size (both on the graph paper, but also in relation to the Word document it is displayed in. Only potential problem is the use of MgO for magnesium oxide. It would have been better if the word name rather than the symbol name had been used because when the graph was drawn there was no way of knowing what the resulting formula for the oxide would have been. Alternatively, it could have been labelled MgxOy to indicate that the ratio was unknown. CalculationsDone in Word, which makes processing easier (easier to mark, and much, much easier to correct).Clearly states the purpose of what they are trying to achieve. Use moles when necessary.All calculated values to 3 significant figures.Gives sample calculations for each type of calculation (in this case there was only one variety, but if e.g. many different metals had been burnt, only one sample calculation showing exactly what was done is needed, for the other metals only the ratios would have needed to be shown. A table is usually best for multiple answers.Correct units used throughout.Clear progression of ideas in the calculation, with explanations throughout as to what is being done. iGCSE Exemplar essayTask: Investigate the properties of the halogens in 300 wordsAstatine - From the Greek for “unstable”3562350169545Figure SEQ Figure \* ARABIC 1. How Astatine is made through the radioactive decay of heavier elementsFigure SEQ Figure \* ARABIC 1. How Astatine is made through the radioactive decay of heavier elementsAt any one time there is less than a gram of astatine in the Earth’s crust, making it the rarest naturally occurring element in the Earth’s crust. Halogens are non-metals and characteristically get darker in colour down the group, have a higher melting point and become less reactive, but because of how radioactive it is it isn’t possible to get a sample of astatine large enough to look at or to measure its boiling point; the heat generated from the radioactivity vaporises the sample too quickly. Scientists have, however, investigated its chemistry, and it does behave like a non-metal because it can form covalent bonds, AtH, and AtBr for instance, and also form anions, At-. Most of its physical properties, however are predicted based on the trends within its group, but these predictions sometimes are in conflict with another trend, that of the metalloids, which are the elements like Si and Po which behave like both metals and non-metals, for instance, some predict it would look like a metal rather than a black solid. Most interestingly, as a metalloid it should be able to form cations, At+ like all other metals, and indeed it can, unlike the other halogens. Although it is relatively easily oxidised, which is unlike the others in its group, and in fact unlike other non-metals, this property does still follow the groups trend which take extra electrons less readily as you go down the group. The ability to lose electrons is a very important characteristic for metals, and astatine demonstrates that both the metalloid trend and the halogen trend in fact converge, in just one element we have evidence for both of these trends. Word count 280Score 13/13CommentsPicture: A good and relevant diagram which demonstrates how larger atoms can become smaller atoms like At. Helps to explain the formation of At whilst also allowing my essay to avoid the physics behind it, which would harm the relevance of my essay to chemistry. 1a, b and c) States the important trends within the halogen group and information about astatine. Then explains why things like the kinds of ions it can form, or if it can be oxidised matters to the argument. Then analyses what this means, that it is part of not only the trend in halogens but also the trend in metalloids, both of which are ultimately based on trends within the structure of atoms. A merit goes to the first student to point this out in class. 1d) Although tackles an element that is not on the syllabus, it makes constant reference to the other halogens and to the trends which they have.1e)Is more than 10% over, but less than 20% so gets both marks. In practice a really good essay might have to go over the word count sometimes, what is essential is that if it does, it doesn’t contain irrelevant material, Use of Englisha, b and c) Correct grammar, and vocabulary used throughout, good grammar and the ideas flow well with there being something that is recognisably an introduction, main bit and conclusionExemplar practical write up: Conclusion and evaluation (CE)Task: Write a Conclusion and Evaluation for the investigation into the effects of salt on the fixed points of water in under 300 words.NOTE: This is only an exemplar for a conclusion and evaluation, it would score very low marks as a Design (D) or a Data Collection and Processing (DCP) lab write up.Design (D)Practical title: Investigating the freezing and boiling points of different salt solutions.Basic idea: When you add salt to a solvent (in this case water) you change its fixed points because it is now a solution, a kind of mixture (pure substances have exact melting and boiling points, this is a test for purity).HypothesisWhen you add more salt both the boiling and melting points will both increase.Basic methodTo a fixed volume of solution add increasing amounts of salt to five different solutions.Heat each solution and measure when it boils.Then cool each solution with ice and take the temperature when it freezes.[How many marks do you think this would get as a design practical? How could it be improved?]Data collection and analysis (DCP)ResultsThe more salt you added the higher the boiling point, BUT the lower its freezing (and melting point).[How many marks do you think this would get as a DCP practical? How could it be improved?]Conclusion and Evaluation (CE)Model Answer1a, 1bWhenever we added more salt the boiling point increased by 2oC for every 2g extra salt we added, but the melting point decreased by 1.5oC for every 2g of extra salt; this shows the hypothesis is half-right.2cThe boiling point of pure water was shown to be 100.5oC which is anomalous (it should be exactly 100oC). There could have been salts in the beaker so that the water wasn’t really pure. 1cThe melting and boiling points of pure water is always 0oC and 100oC, but when we add slat we make a solution which is a kind of mixture. When we add salt to the solution we are adding ions, these make strong bonds with the water that mean it is harder to break liquid water, therefore increased boiling point. 2a, 3bWe should have repeated the experiment to improve the reliability instead of only measuring each salt concentration once, and used a more accurate thermometer. We could have checked the accuracy by measuring known temperatures, e.g. boiling point of distilled water. 2b, 3aWe shouldn’t have used the same salt solution to measure the boiling and freezing points, some water will be lost when we boil it changing the salt concentration, so a fresh solution should be used instead. We should have used distilled water instead of tap water, which has ions in it.3cWe could experiment with different salts, like KNO3, CuSO4 and MgCl2, which will dissolve, and also CaCO3 which won’t, to see if it is dissolving that makes the difference, and to investigate the effects of changing the size of the charges of the ions in solution.Total words: 270, word limit is 300, If you go over by more than 50 words and or you include irrelevant material than you may be penalised and lose marks. This would have gotten full marks 18/18 ................
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