Metric Mission

Overview

Students build and apply a metric conversion understanding for length, mass and capacity. The lesson revises familiar benchmark relationships, then uses a clear conversion strategy to solve calculations and word problems. Year 5 students and students working below Year 6 expectations can work with supported conversions, while Year 6 students apply decimal representations and explain their reasoning.

Learning intentions

Students will:

• recognise the relationships between common metric units;
• convert between mm, cm and m; g, kg and t; and mL and L;
• choose an appropriate unit and operation for a measurement problem;
• solve and explain metric conversion word problems.

Success criteria

• I can state a useful equivalence, such as 1 m = 100 cm or 1 L = 1,000 mL.
• I can decide whether to multiply or divide when converting units.
• I can record an equivalent measurement using a decimal where appropriate.
• I can solve a word problem and explain whether my answer is reasonable.

Curriculum links

• Measurement — converting between common metric units of length, mass and capacity and choosing decimal representations relevant to a problem.
• Number — selecting efficient multiplication and division strategies to solve practical problems.
• Mathematical reasoning and problem-solving — representing, calculating and explaining solutions in context.

Lesson structure (80 minutes)

1. 0–8 min · Hook and diagnostic. Display a picture of a 1 m ruler, a 1 kg bag and a 1 L bottle using the hook and diagnostic slides. Ask: “Which is greater: 250 cm or 2 m? How do you know?” Students silently estimate, then answer three quick questions on mini whiteboards: 1 m = ___ cm, 1 kg = ___ g, 1 L = ___ mL. Note misconceptions without correcting every answer yet.

2. 8–22 min · Build the conversion relationships. Use the metric relationships slides and display the Units Conversion Ladder as a reference. Model that moving to a smaller unit requires more units, while moving to a larger unit requires fewer units: 3 m = 300 cm, 450 cm = 4.5 m, 2 kg = 2,000 g and 1.5 L = 1,500 mL. Explicitly connect prefixes: kilo means 1,000, centi means hundredth and milli means thousandth. Students copy a three-row reference table and explain one example to a partner.

3. 22–35 min · Teacher modelling: operation and notation. Model a consistent routine on the conversion routine slides: identify the given unit, identify the required unit, decide whether the number of units becomes larger or smaller, calculate, then check. Work through 7 m = 700 cm, 6,000 g = 6 kg, 3.25 L = 3,250 mL and 0.8 m = 80 cm. Emphasise that the measurement stays the same even though the number changes. Students solve four “show me” examples on whiteboards and justify “multiply” or “divide” before calculating.

4. 35–53 min · Differentiated practice. Distribute the metric conversion and word-problem worksheet. Students work independently for five minutes, then check selected answers with a partner. The core section includes conversions across the three unit families and short problems such as: “A hiking track is 2.4 km long. How many metres is this?” and “A recipe uses 750 mL of milk. How many litres is this?” Students working at Year 5 level complete whole-number conversions first. Provide the ICP students with the picture-supported matching and fill-the-gap section: 1 m = 100 cm, 1 kg = 1,000 g and 1 L = 1,000 mL, using a place-value chart, concrete measuring items and adult prompting.

5. 53–68 min · Problem-solving teams. Place students in mixed-ability groups of four: reader, unit finder, calculator and explainer, rotating roles for each problem. Display the team challenge slides. Groups solve three practical problems, recording the unit, operation, calculation and sentence answer: a 1.25 m tablecloth compared with 125 cm; 4 kg 500 g converted to kilograms; and 2 L of cordial shared into 250 mL cups. Require groups to identify a common mistake and explain how to correct it. Support students may use the conversion ladder and manipulatives; Year 6 students must include at least one decimal representation.

6. 68–76 min · Review and address misconceptions. Reveal answers on the discussion and error-analysis slides one at a time. Students compare methods, then discuss errors such as writing 5 m = 50 cm or treating 1,200 mL as 1.2 mL. Ask several students to explain why their answer is reasonable, not just state the answer.

7. 76–80 min · Exit check. Students complete the final four questions on the exit-check section: convert 3.6 m to centimetres, 2,500 g to kilograms, 1.75 L to millilitres, and solve “A bottle holds 500 mL. How many bottles fill 2 L?” Collect responses to identify the next teaching focus.

Resources

• the complete metric conversion slide deck
• the metric conversion and word-problem worksheet
• the Units Conversion Ladder
• Mini whiteboards and markers
• Metre ruler or tape measure
• 1 kg classroom object or labelled mass
• 1 L container and 250 mL measuring cup
• Place-value charts and calculators
• Pencils, highlighters and exercise books

Assessment

• Listen to student explanations during the whiteboard check, partner practice and team roles, recording who confuses the direction of conversion.
• Check worksheet strategies, not only answers: students should identify units, choose an operation and write an answer in context.
• Use the exit check to group students for the next lesson: secure, needs practice with decimals, or needs targeted work with unit relationships.

Differentiation

• Support: keep the conversion ladder visible; use colour-coded unit labels, sentence starters (“I changed to a ___ unit, so I…”), concrete measuring equipment and worked examples. Read word problems aloud and highlight the given and required units.
• For the two students working around Year 2 expectations, reduce the number range, focus on the three benchmark facts, use matching and oral responses, and provide one-to-one or teacher aide prompting. For the student working around Year 1 expectations, use only familiar classroom objects, compare “more units/fewer units”, and record answers with drawings or numerals.
• EAL/D support: pre-teach “convert”, “equivalent”, “larger unit”, “smaller unit”, “mass” and “capacity” with gestures and labelled objects; allow partner rehearsal before written answers.
• Extension within the Year 6 task: students compare two equivalent measurements, create a plausible metric word problem involving a decimal, and explain two efficient solution methods.