Use scaffolded prompts to support learners to write about amount of substances in moles
Structure strips can be used to promote independent writing. In this resource learners write about amount of substance measured in moles using key words. They will combine written explanations with calculations to demonstrate and develop their understanding of mole calculations and molar mass.
-
Download this
Stick these structure strips into the margin of a page to support learners to find or retrieve information and write independently about the amount of substances in moles. The resource includes editable writing prompts, an extension question and example answers.
View and download more Structure strips
Learning objectives
- Explain why and how atoms are counted by finding their mass.
- Describe how to find the number of moles of substance in a given mass and vice versa.
- Combine writing with calculations to give a full explanation of chemical concepts.
Introduction
This resource asks learners to demonstrate their thought process, rather than simply using methods they have memorised for carrying out calculations. This will help them to develop deeper understanding. It will also show them how to set out calculations more clearly in exam answers, so that an examiner can follow what they have done, and they can check their own answers more easily.
Chemists count atoms and molecules by finding their mass, in the same way that, if you take bags of change to the bank, the teller will weigh them instead of counting every single coin. The unit of measurement used in chemistry is the mole. If we want to make a certain mass of product, then we need to know how much of our reactants we should start with. Being able to count atoms also allows us to find out the ratio of the different atoms in a substance, so that we can work out its chemical formula.
How to use structure strips
Structure strips are a type of scaffolding you can use to support learners to retrieve information independently. Use them to take an overview at the start of the topic, to activate prior knowledge, or to summarise learning at the end of a teaching topic. For more ideas on how to use structure strips with your learners, see 5 ways to use structure strips effectively.
Structure strips have sections containing prompts, sized to suggest the amount that learners must write. Learners glue the strips into the margin of an exercise book and write their answers next to the sections, in full sentences. When learners have finished using the structure strip, they should have an A4 page set of notes and examples.
The strips are printed five to a page and will need to be trimmed to size. Find them on the second page of the student sheet.
Scaffolding
- Encourage learners to use the suggested key words and phrases in their answers.
- To further support learners, include additional prompts in the structure strip. If learners are struggling to engage with the task, supply them with sentence starters created from the model answers.
- As learners grow in confidence, ask them to attempt the extended answer question first and then use the structure strip to improve or self-assess their answer.
Key words
Nanometre (nm), relative atomic mass, element, relative formula mass, compound, molar mass (g/mol), ratio.
Metacognition
This resource supports learners to develop their metacognitive skills in three key areas.
- Planning: the strips provide scaffolding to plan the written response. Learners will decide where to gather information from (textbooks, own notes, revision websites). Ask learners: is the source of information you are using reliable?
- Monitoring: learners are prompted by the questions in the structure strip and can check their own answer against the prompts. Ask learners: have you covered all of the prompts in the space provided? Do you need to change anything to complete the task?
- Evaluation: learners can self-assess or ask a peer to check their work against the answers. Ask learners: did you achieve what you meant to achieve? What might you do differently another time?
Extended answer question
Instruct learners to answer the question after they have attempted the structure strip. The structure strip activates the required knowledge which learners can then apply to the question.
Consider re-framing the context of this question to one that your learners are more familiar with, to empower them to unlock their existing science capital. Read more about science capital.
Calcium and bromine react together to form calcium bromide:
Ca + Br2 → CaBr2
Alex weighs out 4 g of calcium, and Chris weighs out 4 g of liquid bromine (Br2). Alex says that they have the same amount of each substance, but Chris says they don’t. Explain why Chris is correct and suggest how much of each should be weighed out so that the amounts are the same.
The Avogadro number is 6.02 × 1023. Show how many bromide ions will be in the calcium bromide made if Alex and Chris use the masses you have suggested.
Answers
Suggested answers for the structure strip activity are given in the downloadable teacher notes.
Answer to extended answer question
Alex and Chris have weighed out the same mass of substance. However, in chemistry the amount of substance is the number of moles of that substance. The molar mass of calcium is 40 g/mol, whereas the molar mass of bromine is 2 × 80 = 160 g/mol. The molar mass of bromine is four times greater than that of calcium, so in the same mass of each there will be four times fewer particles of bromine than there are of calcium. Specifically, Alex has weighed out 4 ÷ 40 = 0.1 mol of calcium and Chris has weighed out 4 ÷ 160 = 0.025 mol of bromine.
To have the same number of moles of each, Chris would need to weigh out four times as much bromine, i.e. 16 g. If 0.1 mole of each of calcium and bromine are reacted, 0.1 moles of calcium bromide should be formed. Each formula unit of calcium bromide contains two bromide ions, so there will be 0.2 moles of bromide ions. Therefore, the number of bromide ions will be:
0.2 × 6.02 × 1023 = 1.204 × 1023 bromide ions
Downloads
Structure strip amount of substance in moles 14-16 student sheet
Handout | PDF, Size 0.19 mbStructure strip amount of substance in moles 14-16 teacher notes
Handout | PDF, Size 0.22 mbStructure strip amount of substance in moles 14-16 student sheet
Editable handout | Word, Size 0.43 mbStructure strip amount of substance in moles 14-16 teacher notes
Editable handout | Word, Size 0.43 mb
- Prepare(7)
IdeasWays to teach the mole at 14–16
Use these four ideas to effectively teach and contextualise this crucial chemistry unit
ResourceStudents’ difficulties with stoichiometry | Beyond appearances
Go beyond apperances and clarify the difficulties that students have around “the mole concept”.
IdeasStoichiometry and moles: how to explain it?
Use cooking as a fun, accessible introduction to why and how we use balanced equations
CourseQuantitative chemistry | Self-led course
Build confidence in your quantitative chemistry knowledge and discover effective topic-specific teaching strategies
- Deliver(5)
currently reading
ResourceAmount of substance in moles | Structure strip | 14–16 years
Use scaffolded prompts to support learners to write about amount of substance in moles
ResourceMoles of xenon | Johnstone’s triangle worksheets | 14–16 years
Introduce Johnstone’s triangle as a method of calculating the number of moles of xenon from a given volume of gas
ResourceMoles and volume | Developing understanding | 14–16 years
Deepen your learners’ understanding of the idea that equal volumes of gases contain an equal number of molecules with this worksheet
ResourceMoles of gold | Johnstone’s triangle worksheets | 14–16 years
Connect macroscopic, sub-microscopic and symbolic understanding of calculations involving moles and mass with Johnstone’s triangle
ResourceMoles and mass | Developing understanding | 14–16 years
Develop understanding of the relationship between the mass of one mole, the number of moles and the mass of a substance
- Literacy(1)
ResourceQuantitative chemistry | Key terms support | 14–16
Language support pack for quantitative chemistry, with key terms list, accessible glossary, Frayer models and unscrambling definitions
- Assess(3)
ResourceAmount of substance in moles | Knowledge check | 14–16
Assess learning of amount of substance measured in moles with this higher level worksheet
ResourceAmount of substance in moles | In context | 14–16
Put amount of substance measured in moles into context with questions based on common practical experiments
ResourceQuantitative chemistry | Review my learning | 14–16 years
A set of differentiated worksheets with answers to identify learning gaps and misconceptions on the topic of quantitative chemistry
- Enrich(2)
Games and puzzlesMoles equations | Gridlocks puzzle | 14–16 years
Reinforce your students’ understanding of moles equations using these sudoku-style puzzles, with printable worksheets and answers
CPD articleHow to teach moles at post-16
Use this explainer to help students overcome misconceptions of this fundamental quantity
No comments yet