Mini Minds Hub · Free printable
The Atom Crime Lab: Free Printable Worksheet for Year 9
- ForYear 9
- StageKey Stage 3
- CostFree
- FormatPrintable PDF
The Atom Crime Lab is a free printable science worksheet for Year 9 (ages 13 to 14), in Key Stage 3. Students play lab detectives. They classify six clues as elements, compounds or mixtures, then use the letters to name the culprit.
It comes from the Mini Minds Hub, the free library of printables from Jaques of London, the British games and toy company that has been making games for families since 1795. Print both pages, give page 1 to the student and keep page 2 for yourself. It holds notes, help, a stretch idea and the answers. Black and white printing works well.
What is on the sheet
Students fill in a table with one row for each clue. The columns are Evidence and letter, Particle diagram, Formula and Your verdict. They read the diagram and the formula, then decide whether each clue is an element, a compound or a mixture. Numbered questions follow, including one on Evidence A and one on Evidence F, with space to explain in writing. The letters from the verdicts then name the culprit.
- Evidence and letter
- Particle diagram
- Formula
- Your verdict
- Evidence A is made of joined pairs, yet it is an element. Explain why.
- Evidence F contains iron and sulfur. Why is it not a compound?
Ways to build the skill
Sketch it first
Before choosing a verdict, draw a quick particle picture of any substance you know. Use one symbol for each type of atom. Ask which symbols are present and whether they touch.
Read formulae aloud
Pick formulae from textbooks or product labels. Say which elements the symbols stand for and what the small numbers tell you. Then say what the formula suggests about the atoms.
Sort and defend
Write names of familiar substances on small cards. Sort them into three piles and give a reason for each card. If a reason is weak, move the card and try again.
Atoms, elements, compounds and mixtures
Everything around us is made of atoms. Each type of atom belongs to an element, and the periodic table lists them all. Chemists give each element a symbol of one or two letters. Scientists classify a substance by looking at which atoms it contains and how they are arranged. A particle diagram shows this with circles or shapes, and a formula shows the same thing in symbols and numbers.
The three classes sit at the heart of Key Stage 3 chemistry. An element contains one type of atom only. A compound contains atoms of different elements joined by chemical bonds. A mixture contains substances that are together but not chemically joined, so physical methods such as filtering or evaporating can often separate them. Deciding which class fits a clue means checking both the atom types and the joining.
Quick chemistry facts
- Atoms are far too small to see with a school light microscope.
- Chemical symbols have one or two letters. The first is always a capital.
- A compound can behave very differently from the elements that make it.
- A mixture can often be separated without a chemical reaction.
- Chemists use formulae so that the same substance has the same description everywhere.
Skills and curriculum link
- Reading particle diagrams
- Using chemical formulae
- Classifying substances
- Explaining with evidence
- Scientific vocabulary
Facts that help the detectives
- ElementAn element contains one type of atom only. Look at the symbols or the particle picture and count the types, not the total.
- CompoundA compound contains two or more elements joined together by chemical bonds. Its formula shows the different symbols together.
- MixtureA mixture is made of substances that are together but not chemically joined. Each part keeps its own identity.
- Reading a formulaCapital letters begin each element symbol. A small number after a symbol tells you how many atoms of that element are in the unit.
Key words
- AtomThe smallest part of an element that still has the properties of that element.
- ElementA substance made of one type of atom only.
- CompoundA substance made of different elements chemically joined together.
- MixtureTwo or more substances together but not chemically joined.
- Particle diagramA drawing that uses circles or shapes to show the atoms or particles in a substance.
- FormulaA set of symbols and numbers that shows which atoms are in a substance.
How to use it
- Print both pages. Page 1 is for the student. Keep page 2, which has the notes and answers.
- Read the key words aloud together first. Check everyone can say what element, compound and mixture mean.
- Work through the table clue by clue. Look at the particle diagram and the formula before choosing a verdict.
- Answer the numbered questions in full sentences. Use the word because to give a reason.
- Mark together using page 2. Discuss which verdicts caught people out, then name the culprit.
Help, stretch and game ideas
If it feels too hard
Say aloud: one kind of atom is an element, joined different atoms make a compound, mixed and not joined is a mixture. Cover all but one row of the table. Look at the diagram, then the formula, and decide.
To stretch confident children
Invent a seventh clue with a formula and a particle description. Swap it with a partner to classify. Then each of you writes a one sentence reason to defend your verdict, and you compare.
Make it a game
Work as detectives in pairs. Each pair must agree a verdict and defend it before revealing the culprit's name. If the pair disagrees, they must find the evidence in the diagram or formula that settles it.
Mistakes to watch for
Watch forA student classifies from the formula or the diagram alone and the two seem to disagree.
Try thisUse both. Ask what the diagram shows about atom types and what the formula shows. Check the two tell the same story.
Watch forA student writes a verdict with no reason.
Try thisAsk for a sentence that starts with because. Name the atom types and say whether they are joined.
Watch forA student mixes up compound and mixture.
Try thisAsk one question: are the parts chemically joined, or just together? Then check the diagram for evidence of joining.
Talk about it
- How do you tell an element from a compound in a particle diagram?
- What does a small number in a formula tell you?
- Which clue was hardest to classify, and why?
- How could you separate a mixture without a chemical reaction?
- Why do chemists use symbols and formulae instead of long names?
- How did the evidence help you narrow down the culprit?
Take it off the page
Atom cards
Make a set of cards, each with an element symbol. Build pretend formulae by laying cards in a row, then say what each formula would show.
Mixture hunt
Look for mixtures at home, such as in a snack or a drink. Talk about how you could separate the parts and what would stay the same.
Design a lab report
Write a short report for a made up case. Include a table of evidence, a verdict for each item and one sentence of reasoning.
Who it is for
Parents
Sit beside your child for the first clue, then let them lead. You do not need to be a chemist. Use the help line on page 2 and ask them to explain each verdict aloud.
Teachers
Use it as a starter, plenary, early finisher task, supply resource, homework or table activity. It needs no preparation beyond printing. Page 2 gives support, stretch and answers for mixed ability groups.
Home educators
Pair it with books, kitchen cupboard observations and everyday talk about materials. Because the sheet is free and printable, you can reuse it for brothers and sisters or for revision later.
Where this fits in learning
Before this sheet, students meet the idea that matter is made of particles and learn how solids, liquids and gases differ. They also learn that substances can be pure or mixed, and they start to read simple symbols.
After it, students move on to chemical reactions, the periodic table in more detail and methods of separation. At GCSE these ideas grow into bonding, writing equations and explaining why substances behave as they do.
Questions parents and teachers ask
- What age is The Atom Crime Lab for?
It is written for Year 9 (ages 13 to 14), in Key Stage 3. Learners are moving from remembering facts to applying them, so it suits students who can read a formula and explain a choice.
- What will students practise?
Students practise classifying substances as elements, compounds or mixtures from particle descriptions and formulae. They also practise explaining a decision with evidence in writing, which is a key part of working scientifically.
- How do I use it?
Give each student the sheet and a pencil. Read the key words aloud first. Mark together using page 2, then discuss which verdicts caught people out. Work through it together the first time.
- What if it feels too hard?
Say aloud: one kind of atom is an element, joined different atoms make a compound, mixed and not joined is a mixture. Then work on one row of the table at a time and talk through each choice.
- Is it free?
Yes. It is free to print for home and classroom use. You can print it again for other students or for revision, and black and white printing works well on plain A4 paper.
- How long does it take?
It depends on the student. Some will finish quickly and others will want to discuss each clue. You can split it across two sittings, or use the stretch idea on page 2 to extend it.
- Can teachers and home educators use it?
Yes. Teachers can use it as a starter, plenary, homework or table activity. Home educators and tutors can use it alone or within a wider science plan. It needs no preparation beyond printing.
Preview the full PDF
Made by Jaques of London, making games for families since 1795. A printable supports classroom learning and does not replace a teacher.