Chemistry Department’s iGCSE ... - Web viewPractical write up (based on the IB. Design. ......

Chemistry Department’s iGCSE Assessment Guidebook (DRAFT)Basically there are these main standardised ways we assess students achievement

1. End of topic tests (using only questions from CIE past exam papers)2. Practical write up (based on the IB

a. Designb. Data collection and processingc. Conclusion and evaluation

3. Essays, using a rubric based on the extended essay rubric 4. Mini-symposia focusing on ToK, using a rubric based on the one issued for the ToK presentation5. Other 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 class

For 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 problem

D1a You have provided a focused research question of what you intend to do. /2

D1b You have given a qualitative hypothesis and justified it with quantitative scientific reasoning (using a calculation or chemical equation).

/2

D1c You attempt to explain the scientific reasoning behind the most important variables you are going to control.

/2

D2 - Selecting variables

D2a States the independent variable (the one you change) /1

D2b States the dependant variable (the one you measure) /1

D2c States the controlled variable(s) (the one(s) that must be kept constant) /2

D3- Developing a method for collection of data

D3a Selects and names appropriate apparatus and materials needed /2

D3b Designs a method that allows for the effective control of the variables /2

D3c Designs a method that allows for the collection of sufficient relevant data /2

Total marks /16

www.SmashingChemistry.com of 18

http://www.SmashingChemistry.com/

Data Collection and Processing (DCP)DCP1

Collect and organize raw data

DCP1a You have successfully recorded all raw data (qualitative and/or quantitative). /2

DCP1b

You have presented the raw data in a complete and clear manner. /2

DCP1c You 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.

/2

DCP2

Processing raw data

DCP2a You have always made the correct calculations with the raw data. /2

DCP2b

You have always used the correct units and significant figures in your solutions to calculations.

/2

DCP2c You 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.

/2

DCP3

Presenting processed data

DCP3a You 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.

/2

DCP3b

When 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.

/2

DCP3c If 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.

/2

Total marks /18

Manipulative Skills (MS)MS1- Instruction

MS1a You have followed VERBAL instructions /2

MS1b You have followed WRITTEN instructions /2

MS1c You are aware of all instructions about HEALTH & SAFETY /2

MS2 - Technique

MS2a You have completed the practical is a sensible way /2

MS2b You have completed the practical in a safe way /2

MS3- D3a You have made sure everyone in the group has done a fair amount of work /2



Teamwork D3b You have worked effectively and efficiently in your group /2

Total marks /14



iGCSE Chemistry Literature Review and Essay Marking Scheme

There 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.

1. Demonstrating an Understanding of Chemistry (UC)

a) KnowledgeDescribes, states or lists relevant information relating to the topic covered by the title.

b) 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.

c) Analysis/ConclusionUses the information that they have provided to identify or explain any trends or larger ideas that this information supports.

d) 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.

e) 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.



2. Demonstrating an understanding of good Scientific Writing (SciW)

a) Research

Uses three or more sources of information and provides a complete bibliography.

b) Depth

The 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.

c) Insight and originality

Choses an unusual or interesting topic to base the essay around, or uses an unusual and interesting approach to their essay.

d) Flair

Demonstrates a thorough understanding of the subject that goes well beyond the syllabus and whilst exploring larger ideas, is obviously aware of the syllabus.

e) 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.

f) 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 English

You 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.

a) Use of correct vocabulary

Vocabulary, especially keywords, are correctly used and defined where necessary

b) Use of correct grammar

Uses grammar correctly

c) Flow 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 all

0/2Partially complete

1/2Complete

2/2Exceptional

3/2Neat and tidyClear writingFull notesDates?Titles?All work stuck into the bookTotal Score: /12Score 0-4 5-8 9-12 Above 12Possible AtL on report 4 3 2 1



1/2Complete

2/2Exceptional




1/2Complete

2/2Exceptional




Checking Notes in TOPIC BooksNot at all


1/2Complete

2/2Exceptional

3/2Clear 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: /12Score 0-4 5-8 9-12 Above 12Possible AtL on report 4 3 2 1



1/2Complete

2/2Exceptional




1/2Complete

2/2Exceptional

3/2Neat and tidyClear writingFull notesDates?



Titles?All work stuck into the bookTotal Score: /12Score 0-4 5-8 9-12 Above 12Possible AtL on report 4 3 2 1

Presentation Rubric (Adapted from ToK)

A Identification of knowledge issue• Did the presentation identify a relevant knowledge issue involved, implicit or embedded in a real-life situation?

Descriptor Achievement level

• Level 1 was not achieved. 0• The presentation referred to a knowledge issue but it was irrelevant to the real-life situation

under consideration. 1–2• The presentation identified a knowledge issue that was in some ways relevant to the real-life situation

under consideration. 3–4• The presentation identified a knowledge issue that was clearly relevant to the real-life situation

under consideration. 5

B Treatment of knowledge issues• Did the presentation show a good understanding of knowledge issues, in the context of the real-life situation?


• Level 1 was not achieved. 0• The presentation showed some understanding of knowledge issues. 1–2• The presentation showed an adequate understanding of knowledge issues 3–4• The presentation showed a good understanding of knowledge issues. 5

C Knower's perspective• Did the presentation, particularly in the use of arguments and examples, show an individual approach

and demonstrate the significance of the topic?


• Level 1 was not achieved. 0• The presentation, in its use of arguments and examples or otherwise, showed limited personal

involvement and did not demonstrate the significance of the topic. 1–2• The presentation, in its use of arguments and examples or otherwise, showed some personal

involvement and adequately demonstrated the significance of the topic. 3–4• The presentation, in its distinctively personal use of arguments and examples or otherwise, showed

clear personal involvement and fully demonstrated the significance of the topic. 5

D Connections• Did 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.www.SmashingChemistry.com of 18



• Level 1 was not achieved. 0• The presentation explored at least two different perspectives to some extent. 1–2• The presentation gave a satisfactory account of how the question could be approached from different

perspectives, and began to explore their similarities and differences.

3–4• The presentation gave a clear account of how the question could be approached from different

perspectives and considered their implications in related areas. 5

iG Rubric Creating Exam Questions

Standard 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 Questions

Question style -2 marks2 All of the questions are of the same style as you would find in a real exam1 Some of the questions are in the wrong style e.g. like true/false questions0 All of the questions are in the wrong style

Level of challenge -2 marks2 All of the questions are set to an appropriate level of challenge1 There is an inappropriate level of challenge to be used by iGCSE0 The level of challenge is totally inappropriate

Use of Command words – 2 marks2 Command words used consistently and appropriately for all questions1 Some inappropriate use of command words 0 Command words totally missing or consistently used inappropriately

Clarity of task – 2 marks2 The questions use precise language and it is obvious what you are supposed to do1 There is some degree of ambiguity in in the language used so that it is not always obvious what is being

asked.0 It I s really unclear what is needed to do to answer the question successfully

Breadth of syllabus coverage – 2 Marks2 There is an excellent coverage of the syllabus1 Some important aspects of the syllabus have been missed out Essential Mark SchemeMark scheme styleAppropriate number of marksMarks linked to the appropriate grade

Paper specific criteriaPaper 1Right number of answersAppropriate style of answersPaper 3Calculations are correctChemical equations are appropriatePaper 6



Graph 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 solution

1b) Hypothesis: Adding salt will reduce the freezing point but increase the boiling point

NaCl (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, oC

1c &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 thermometer

3a, 3b & 3c) Method

1. Add a thermometer that goes up to 200oC to 100 cm3 of a salt concentration heat with an electric heater set to 200oC.

2. Heat each solution and measure the temperature when it boils.3. 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.4. Repeat 2 times for the same salt concentration.5. Repeat steps 1 to 4 for each different salt concentration.

Word count: 231

Score: 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 Exemplar

When 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 data

Record all raw data (qualitative and/or quantitative) /2Presents raw data clearly /2Uses correct headings, units and significant figures.

/2

2 – Processing raw data

Makes the correct calculations on the raw data /2Pays attention to units, significant figures and decimal places in final answer.

/2

Extracts relevant data from the graph if drawn (intercept, gradient etc.) /23 – Presenting processed data

Presents the processed data appropriately (correct choice of graph, bar chart etc.)

/2

Chooses an appropriate scale and plots points/displays processed data correctly/adds trendline and gives equation for trendline

/2

Uses correct labels, units and line of best fit drawn (if graph chosen) /2

Total marks available: 18



Results table (1a,1b and 1c):

Calculations (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 0.0417/0.0350 or 1.000 : 0.840

Rounding we get: 1:1 of Mg:O

Empirical formula is MgO


0.08

0.04


Graph (2c, 3a,3b and 3c)

18/18 (full marks)



Comments Results table

All 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.

Graph Drawn 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.

Calculations Done 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 essay



Task: Investigate the properties of the halogens in 300 words

Astatine - From the Greek for “unstable”

At 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 280


Figure 1. How Astatine is made through the radioactive decay of heavier elements


Score 13/13

Comments

Picture: 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 English

a, 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 conclusion

Exemplar 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).

Hypothesis

When you add more salt both the boiling and melting points will both increase.

Basic method

1. To a fixed volume of solution add increasing amounts of salt to five different solutions.2. Heat each solution and measure when it boils.3. 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)Results

The 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 Answer

1a, 1b Whenever 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.

2c The 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.

1c The 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, 3b We 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, 3a We 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.

3c We 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



Chemistry Department’s iGCSE ... - Web viewPractical write up (based on the IB. Design. ......

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