Exploring Equivalent Capacity

Overview

Unit Title: Capacity Counts: Litres & Millilitres
Lesson Number: 2 of 3
Lesson Title: Understanding Equivalent Capacities
Year Group: Year 3
Subject: Mathematics
Time Allocation: 60 minutes
Class Size: 19 pupils
Curriculum Alignment:
National Curriculum for Mathematics – KS2 (Year 3), Measurement

• Objective: Measure, compare, add and subtract: lengths (m/cm/mm); mass (kg/g); volume/capacity (l/ml)
• Success Criteria:
  • Recognise the relationship between litres and millilitres
  • Confidently convert between litres and millilitres
  • Use knowledge of equivalent measurements to solve problems
  • Collaborate effectively in pairs to create an equivalent capacity chart

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Learning Intentions

By the end of the lesson, pupils will:

• Understand that 1 litre = 1000 millilitres
• Use and convert between litres and millilitres using visual and numerical reasoning
• Identify equivalent capacities in different formats
• Strengthen their mathematical communication and reasoning by working with partners

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Vocabulary

• Capacity
• Volume
• Litre (l)
• Millilitre (ml)
• Equivalent
• Convert

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Resources

• Large clear measuring jugs (marked in ml and l)
• Water or coloured water
• Transparent plastic bottles (labelled with various volumes: 250ml, 500ml, 1l)
• Dry wipe boards and markers
• Millilitres and litres conversion card sets
• Interactive capacity matching game cards
• Printed A3 Equivalent Capacity Table templates
• Capacity Riddle Cards for extension
• Towels/spill cloths for practical activities
• Digital visualiser or camera for demonstration

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Previous Learning

In lesson 1, pupils explored estimating and measuring capacities using millilitres and litres, gaining hands-on experience pouring and reading scales.

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Differentiation

• Support: Visual cues and worked examples on desk mats; support from TA if available
• Challenge: Extension riddles involving multi-step conversions; mental maths conversion challenges
• EAL / SEN: Use of pictorial aids and bilingual measuring charts if required, with buddy support system

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Lesson Structure

⏱️ Starter (10 mins) – "What's in My Jug?"

Objective: Revise key vocabulary & activate prior knowledge

Activity:
With several labelled jugs on the front table (some in ml, some in l), pupils play an "I Spy" game. For example:
"I spy something that holds more than 500ml but less than 1 litre."

Pupils hold up mini whiteboards with their answers.

Key Questions:

• “What helps you know it’s more or less than a litre?”
• “How do millilitres and litres relate to each other?”

Use this to revisit 1 litre = 1000 millilitres with visuals.

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🧪 Main Input (15 mins) – Visual Conversions

Objective: Establish understanding of equivalence between l & ml

Activity: Use a digital visualiser or demonstration tray at front.

1. Show 1-litre measuring jug filled with water.
2. Pour it into 4 x 250ml bottles, asking students to estimate what will happen.
3. Repeat with 2 x 500ml; then 10 x 100ml cups.

Record conversions as equations:

• 1l = 1000ml
• 500ml + 500ml = 1000ml = 1l
• 250ml x 4 = 1000ml = 1l

Talk Task: Pupils turn and talk: “What do you notice?” “What stays the same?”

Stretch Thinking: "If I had half of a litre, how many millilitres is that?" (Answer: 500ml)

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🎯 Paired Activity (20 mins) – Mix & Match Maths

Objective: Practise working with equivalent capacities using reasoning

Set-Up:

• Each pair receives a capacity conversion card set (e.g. 750ml, ¼ litre, 2 × 500ml, etc.)
• Pupils must match cards with equivalent values and sort into ‘Equal’ and ‘Not Equal’ groups
• Once sorted, pupils transpose their findings into their own Equivalent Capacities Chart (on A3 template)

Teacher to circulate: Ask guiding questions such as:

• “How did you know these were the same?”
• “Could there be another way to show 1 litre?”

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🎲 Game Challenge (10 mins) – Capacity Snap!

Objective: Reinforce understanding through a fast-paced game

• Teacher randomly calls out values using either ml or l (e.g. "500ml", "Half a litre", "100cl")
• Pupils snap their hands on the capacity card with the equivalent amount
• The pair with the correct snap explains why the match is valid

Extension: Pupils create their own additional riddle-style cards or clues to test the class

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✔️ Plenary (5 mins) – Exit Ticket

Each student completes a mini exit ticket answering:

Q1: How many millilitres are in 1 litre?
Q2: Two bottles each hold 600ml. What is their total capacity?
Q3: Write two different ways to show 1 litre using millilitres.

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Assessment for Learning

• Formative: Observe group discussions and sorting cards
• Questioning: See depth of reasoning in partner explanation tasks
• Exit Ticket: Quick check on individual understanding and conversion ability

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Reflection & Next Steps

Transition into Lesson 3: In the next session, pupils will use their knowledge of conversions to solve real-world word problems involving capacity. This will extend to include addition and subtraction of mixed units (e.g. 1.5l + 750ml), supporting fluency and multi-step reasoning.

If pupils showed strong understanding, introduce decimals (e.g. 1.25l) in extension activities next time. If gaps remain around equivalency basics, revisit with further visuals and group games.

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WOW Factor Teacher Tips 🌟

• Use food dye to colour the water—this creates more visual engagement during pouring!
• Turn the final 5 minutes into a "Mystery Liquid Lab", verifying if mystery bottles are labelled correctly using estimation based on all they’ve learned
• Use pupil iPads (if available) to create a time-lapse of the pouring demonstration and post it on your class learning wall

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Teacher Notes

• Pupils at this stage benefit significantly from concrete to pictorial to abstract progression.
• Reinforce place value understanding (especially the multiples of 100 and 1000) alongside measurement.
• Encourage use of mathematical vocabulary consistently during challenges and chart completion.

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End of Lesson 2 – Capacity Counts Unit – Year 3 Mathematics