Metric Moves

Overview

Students connect metric conversions to base-10 place value, then apply this understanding to practical measurements of length, mass and capacity. They build on prior knowledge of common units, decimals and place-value partitions by explaining why the numerical value changes when the unit changes.

Learning intentions

Students will:

• convert between common metric units using multiplication or division by powers of 10
• represent measurements as decimals and equivalent compound measures
• measure length, mass and capacity accurately in a practical context
• estimate and explain whether an answer is reasonable.

Success criteria

• I can identify whether the new unit is larger or smaller.
• I can use a place-value table to convert a measurement.
• I can explain why the number increases for a smaller unit and decreases for a larger unit.
• I can record a sensible decimal measurement with the correct unit.

Curriculum links

• Measurement — converting between common metric units of length, mass and capacity and choosing decimal representations relevant to a problem.
• Number — applying place value to decimal calculations and using estimation to check reasonableness.
• General capabilities — Numeracy, critical and creative thinking, and personal and social capability through collaborative problem-solving.

Prerequisite knowledge

Students should know millimetres, centimetres, metres, kilometres, grams, kilograms, millilitres and litres; understand that 10 of one place equals 1 of the next place; read decimals to at least hundredths; and use a ruler, balance and measuring jug safely.

Vocabulary

metric system, unit, convert, equivalent, length, mass, capacity, millimetre, centimetre, metre, gram, kilogram, millilitre, litre, decimal, place value, estimate, smaller unit, larger unit.

Lesson structure (60 minutes)

1. 0–5 min · Hook and predict. Display a 1-metre strip and ask: “Will the number be larger or smaller if I describe this in centimetres? Why?” Open with the prediction and visual hook slides. Students make a prediction, discuss with a partner and justify it using “smaller unit” or “larger unit”.

2. 5–17 min · Explicit teaching and model. Use the metric conversion teaching slides and draw a place-value table labelled km, m, cm, mm and kg, g, then L, mL as appropriate. Teacher explains that metric prefixes and place-value shifts are based on 10: converting to a smaller unit creates more units, so the numerical value increases; converting to a larger unit creates fewer units, so it decreases. Model:

• 1.24 m = 124 cm, because each metre contains 100 centimetres.
• 1.24 m = 1 m + 2 dm + 4 cm, showing the decimal places as tenths and hundredths of a metre.
• 2.5 kg = 2500 g.
• 1.75 L = 1750 mL. Students annotate the place-value movement and estimate each answer before checking it.

3. 17–23 min · Guided reasoning. Present “0.6 L = ___ mL”, “4500 g = ___ kg” and “3.2 m = ___ cm” on the guided examples and reasoning prompts. Teacher asks, “Is the target unit smaller or larger? Should the number increase or decrease?” Students solve on mini-whiteboards, hold up answers and explain one conversion using a sentence frame: “The unit is ___, so the number ___ because ___.”

4. 23–43 min · Collaborative measurement stations. Arrange groups of four with roles: measurer, recorder, equipment manager and checker. Distribute the metric measurement investigation sheet. Groups rotate through three tasks, spending about 6 minutes at each:

• Length: measure classroom objects in centimetres and metres; record one measurement in both units.
• Mass: measure prepared objects on a balance in grams and kilograms; record an equivalent decimal.
• Capacity: measure water in a jug or cylinder in millilitres and litres; record an equivalent decimal. Students estimate first, measure carefully, convert, and check whether the converted value is reasonable. Teacher circulates, questioning unit choice and checking recording accuracy.

5. 43–53 min · Share and address misconceptions. Return to the station review and discussion slides. Invite groups to share one conversion and its explanation. Compare errors such as “1.75 L = 175 mL” and ask students to use a place-value table or repeated addition to correct it. Students revise their worksheet and explain how the decimal representation suits the context—for example, 1.75 L for a bottle or 1750 mL for a measuring jug.

6. 53–60 min · Exit assessment and reflection. Display the exit-ticket and reflection slide. Students independently answer:

7. Convert 1.24 m to centimetres.

8. Convert 2500 g to kilograms.

9. Explain why a number increases when changing to a smaller unit.

10. A container holds 1.75 L. Write this in millilitres and state which representation is more useful for filling a 250 mL cup. Students hand in the exit ticket before leaving and rate their confidence from 1 to 3.

Resources

• the metric conversion slide deck
• the metric measurement investigation sheet
• Metre rulers, 30 cm rulers and tape measures
• Digital or pan balances
• Measuring jugs or graduated cylinders
• Empty containers labelled with capacity
• Classroom objects and prepared masses
• Water trays, towels and paper
• Mini-whiteboards, markers and pencils

Assessment

• Listen for explanations linking unit size to numerical change during prediction, guided examples and station work.
• Check worksheet estimates, place-value reasoning, correct units and conversions; question students who move the decimal without explaining why.
• Use the exit ticket to identify students needing further work with powers of 10, decimal place value or selecting an appropriate representation.

Differentiation

• Support: provide a visible conversion chart, colour-coded place-value tables, pre-labelled equipment and sentence frames such as “___ is smaller than ___, so I multiply by ___”. Pair students strategically and allow calculators after the reasoning has been shown.
• Support EAL/D and students requiring adjustments with real objects, gesture, diagrams, repeated modelling and reduced recording demands. Read instructions aloud and check understanding at each station.
• Extension: ask students to design a measurement clue involving two units, such as “A mass is between 2 kg and 3 kg and equals 2750 g”, then swap and solve it.
• Challenge confident students to choose the most useful representation for a specific purpose and defend their choice, such as litres for a drink bottle or millilitres for a medicine measure.

Safety and management notes

Keep water containers on trays and wipe spills immediately. Establish walking routes and one equipment manager per group. Check balances are on stable surfaces, prohibit tasting or drinking water, and model safe handling of equipment. Prepare stations before students enter the practical phase.