You will learn
- Define filtration.
- Build a filter.
- Predict what passes through.
- Evaluate how clean the filtrate is.
Version 0.2 · expanded edition · built from cited public sources Content is based on the official frameworks and sources listed under Sources and standards. No official endorsement is claimed. Written in the style of common primary school assessments. No exam result is promised.
Student lesson
- Filters trap insoluble solids.
- Dissolved substances pass through.
- Residue stays; filtrate passes.
- Filters clean muddy water but not germs.
Words to know
separating solids from liquids using a filter
paper with tiny holes
the solid left on the filter
the liquid that passes through
1. Discover: The muddy water
After rain the village stream is muddy. Mawuli pours muddy water through a cloth. Mud is trapped and cloudy water becomes less cloudy. “Filters only remove bigger pieces,” says his aunt. “We still need to boil or treat the water before drinking.”
Think: What is the residue?
2. Understand: Filtration
Idea 1: How it works
A filter has holes smaller than the solid pieces. The solid stays as residue and the clear liquid, the filtrate, passes through.
Idea 2: What passes through
Dissolved salt or sugar are too small to be trapped, so they pass through with the water. Filtering cannot separate solutions.
Idea 3: Water safety
Filtering muddy water makes it clearer but not safe. Drinking water also needs treatment such as boiling or chlorine from a trusted source.
3. Worked examples
Example 1 (I show you): Name
Left on paper.
- Residue.
- Solid.
- Trapped.
Answer: Residue.
Example 2 (We do it together): Name
Passes through.
- Filtrate.
- Liquid.
- Clear.
Answer: Filtrate.
Example 3 (You try): Predict
Salt water.
Show the steps and answer
- Dissolved.
- Passes.
- Not removed.
Answer: Salt passes through.
Did you know?
City water works use layers of sand and gravel as huge filters before treating water.
Why this matters
Filtration helps clean water and make coffee, tea and medicines.
4. Explore: Build a filter
Make muddy water, filter it through paper, cloth and a sand layer and compare clarity.
- Make muddy water.
- Fold filter paper in a funnel.
- Pour slowly.
- Compare filtrates.
Think about it: what did you notice?
What did you notice? Paper gave the clearest filtrate but it was still not safe to drink.
5. Practise
Say it in a sentence
Use these starters when you talk about the lesson. Say them out loud.
- ___ separates solids from liquids.
- The solid left is the ___.
- The liquid that passes is the ___.
- ___ paper has tiny holes.
Guided practice
Question 1. What is filtration?
Separating.
Question 2. What is residue?
Solid left.
Question 3. What is filtrate?
Liquid through.
Independent practice
Level 1: Start
- What is filtration?
- What is residue?
- What is filtrate?
- Does salt pass?
- Is filtered water safe?
Level 2: Grow
- Why holes?
- Why not safe?
- Why layers?
Level 3: Stretch
- Build a filter.
- Compare clarity.
- Explain.
Answers are in the answer key below. Try first, then check.
6. Apply: Science in everyday life
Explain why filtered muddy water is still unsafe.
Show a sample answer
Mention germs.
Another one. Tell a family member one thing from this lesson. Use the words you learned.
Show a sample answer
A clear sentence that uses at least one word from Words to know.
7. Common mistakes
Fix: Not always.
Fix: No.
8. Lesson summary and revision card
- I can define filtration.
- I can build a filter.
- I can predict what passes through.
- I can evaluate how clean the filtrate is.
9. Check and master
Answer all 14 questions. You will see feedback after each one.
Your result appears here after you answer every question.
10. Key takeaways
- Filters trap insoluble solids.
- Dissolved substances pass through.
- Residue stays; filtrate passes.
- Filters clean muddy water but not germs.
11. Next lesson
Next lesson: Evaporation and separation. Keep going with the next idea in this course.
Exam practice
These questions are written in the style of common school and international primary assessments. Try them on your own, without looking back. Then check your answers in the marking guide. The marks are shown in brackets.
- Define residue and filtrate. [2 marks]
- Explain what passes through a filter. [3 marks]
- Explain why filtering is not enough. [3 marks]
- Safety rule. [2 marks]
Total: 10 marks.
Marking guide and model answers
- 1 each
- Liquid [1]; dissolved substances [1]; reason [1]
- Germs [1]; treat [1]; examples [1]
- Any [1]; reason [1]
Score guide: 9 to 10 = secure. 6 to 8 = nearly there, revise the parts you missed. Under 6 = work through the lesson again with a grown-up.
Printable worksheet
- What is filtration?
- What is residue?
- What is filtrate?
- Does salt pass?
- Is filtered water safe?
- Why holes?
- Why not safe?
- Why layers?
- Build a filter.
- Compare clarity.
Homework
Describe how a coffee filter works.
Answer key and marking scheme
| Question | Expected response | Marks |
|---|---|---|
| 1. What is filtration? | Separating. | 1 |
| 2. What is residue? | Solid left. | 1 |
| 3. What is filtrate? | Liquid through. | 1 |
| 4. Does salt pass? | Yes. | 1 |
| 5. Is filtered water safe? | No. | 1 |
| 6. Why holes? | Trap. | 1 |
| 7. Why not safe? | Germs. | 1 |
| 8. Why layers? | Clearer. | 1 |
| 9. Build a filter. | Photo. | 1 |
| 10. Compare clarity. | Table. | 1 |
| Total | 10 |
Independent practice answers. Level 1: 1 Separating.; 2 Solid left.; 3 Liquid through.; 4 Yes.; 5 No.. Level 2: 1 Trap.; 2 Germs.; 3 Clearer.. Level 3: 1 Photo.; 2 Table.; 3 Sentence..
Quiz answers: 1 B, 2 C, 3 A, 4 B, 5 C, 6 A, 7 B, 8 C, 9 A, 10 B, 11 C, 12 A, Challenge 1 B, Challenge 2 C.
Mastery and remediation
| Objective | Bronze (Developing) | Silver (Proficient) | Gold (Advanced) |
|---|---|---|---|
| O1 Define filtration | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O2 Build a filter | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O3 Predict what passes through | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O4 Evaluate how clean the filtrate is | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
Courseversity badge thresholds (overall quiz score): Gold = 90–100%; Silver = 80–89.9%; Bronze = 70–79.9%. A badge is never a full record of progress.
If a learner struggles
- Find the misconception: “Filtered water is safe to drink.” Not always.
- Explain another way: use real objects, pictures or actions first, then words.
- Show a simpler example: Explain filtration.
- Guided practice: work through one example together and let the learner try the next one.
- Reassess: use the quiz again or the worksheet.
- Move on when the learner shows Silver-level evidence independently.
For parents and guardians
In this lesson your child builds a filter. You do not need to be an expert to help.
- Watch a coffee filter.
- Ask “What is left behind?”
- Never drink science water.
- Ask “how do you know?” after each answer, and listen.
- Praise effort, not only right answers. Mistakes are how we learn.
- Ten to fifteen minutes a day is better than one long session.
Teacher package
1–5. Objectives, prerequisites, materials, preparation, duration
Lesson objectives. Learners will: define filtration; build a filter; predict what passes through; evaluate how clean the filtrate is.
Prerequisite knowledge. Grade 4 ideas: properties of materials, states of matter, melting, freezing, evaporation, dissolving and reversible changes.
Materials. Funnel, paper, muddy water. Low-resource options: use chalk or charcoal on a board or wall, drawings in the sand, and objects from the classroom instead of printed materials.
Preparation. Make mud.
Suggested duration. 45–60 minutes. It can be split into two shorter sessions.
6–9. Teaching procedure, explanation notes, guided and independent activities
Introduction (5 min). Show muddy water and ask, “How can we clean it?”
Explanation (10 min). Teach filtration.
Guided activity (10 min). Learners filter.
Independent activity (10 min). Learners evaluate.
Assessment and reflection (5 min). Ask each learner to say one thing they learned and how they know it.
Key questions. What stays? What passes? Safe?
Teacher explanation notes. Start with real objects and safe, hands-on observation. Then talk about what was seen, then draw and write. Always say “how do you know?”. Keep to the safety notes, and use local, safe materials.
10–12. Differentiation, formative assessment, common misconceptions
Support. Use real objects and pictures, short sentences and a partner. Let learners point, show or draw instead of writing. Extension. Ask learners to find a new example at home and explain how they know.
Formative assessment. Listen to learners read and explain, ask “how do you know?”, and check the independent work.
Misconceptions. “Filtered water is safe to drink.” Not always.
13–15. Assessment questions, answer keys, marking scheme
Use the quiz, the 10-mark exam practice and the worksheet on this page. All answers and marking guides are in the answer sections above. Re-check every answer before use.
16–19. Remediation, enrichment, homework, teacher reflection
Remediation. Explain filtration. Enrichment. Look for one new example near your home or school, draw it and explain it to someone. Homework. See above.
Teacher reflection. After teaching, record: which ideas learners understood; which misconceptions occurred; which activities worked; which learners need more practice; and what to improve next time.
Sources and standards
This lesson is based on the sources below, and no official endorsement is claimed. Reference starting points: Next Generation Science Standards, Cambridge Primary Science and the IB Primary Years Programme. Where a standard code is named, it points to the official framework.
Research used to shape this lesson. Courseversity Science curriculum, Grade 5 Unit 4, topic 8; Next Generation Science Standards, structure and properties of matter; Cambridge Primary Science Stage 5, chemistry: states of matter and materials; IB Primary Years Programme, how the world works. These sources informed the lesson.