Weight Measurement

Overview

In this lesson, students learn which metric units are used to measure everyday weights and practise comparing masses using grams (g) and kilograms (kg). This builds on prior knowledge of measurement and supports later estimating and ordering with sensible benchmarks.

Learning intentions

• Students will use grams and kilograms to measure and compare weights of everyday objects.
• Students will identify appropriate metric units for different items (for example, g for small objects and kg for heavier items).
• Students will make simple estimates using known benchmarks (1 kg = 1000 g, and common mass references).
• Students will explain which unit they used and how they know one weight is heavier or lighter.

Success criteria

• I can choose whether to use grams or kilograms for an everyday item.
• I can read a scale with labelled markings and record mass in g or kg.
• I can compare two objects using the same unit (g with g, or kg with kg).
• I can estimate a mass and check if it is reasonable by measuring.

Curriculum links

• Measurement — VC2M3M01: identify which metric units are used to measure everyday items; use familiar measurements to make estimates.
• Measurement — VC2M3M02: measure and compare objects using familiar metric units and instruments with labelled markings.

Lesson structure (60 minutes)

1. 0–6 min · Hook (Benchmarks talk). Teacher shows two pictures/objects: a bag of lollies and a small tin of soup, and asks: “Which unit would we use—grams or kilograms—and why?” Students do a quick think-pair-share and justify their choice.
2. 6–14 min · Mini-teach (g vs kg). Teacher demonstrates using a scale (or visual scale) and models unit choice: “This small item is likely a few hundred grams, so we use g. This bigger item is likely about a kilogram, so we use kg.” Students complete a short “Unit choice” board response (no writing yet, just point and explain).
3. 14–26 min · Scale familiarisation. Teacher models measuring one item carefully: place object centred, wait for the reading to stabilise, read the labelled markings, and record with the correct unit. Students practise in pairs with one “trial” object each, recording a measurement on their worksheet.
4. 26–40 min · Me asurerestation (guided stations). Teacher sets up 3–4 stations with different objects (light, medium, heavier) and one scale per station. Students rotate:

• Measure 3 objects and record mass in g or kg.
• Compare two objects from their station: “Object A is heavier than Object B by ___ (in the same unit).” Teacher circulates, checking correct unit use and safe handling, and prompts students to reread units.

5. 40–52 min · Compare and explain (whole-class share). Teacher selects 3–4 student results (anonymous if needed) and asks: “Which comparisons are correct? What might be the common mistake?” Students vote and explain what was done well (for example, converting or comparing in the same unit).
6. 52–58 min · Exit ticket (estimate then measure). Teacher gives an item (or picture) and asks for an estimate first, then measures as a check. Students write: estimate in g or kg, measured mass, and a reason whether their estimate was reasonable.
7. 58–60 min · Wrap. Teacher summarises key ideas: correct unit choice and comparing using the same unit. Students state one new strategy they will use next time.

Resources

• Digital or mechanical kitchen-style scales with clear labelled markings
• Assorted classroom objects: small (100–500 g), medium (500 g–900 g), heavier (1–2 kg), including one “tricky” item around 1 kg
• Measurement recording sheets with columns for object name, unit (g/kg), and mass reading
• Station cards (what to measure, how many, and comparison prompt)
• Teacher demonstration object set
• Exit ticket slips and pencils
• Non-slip mats for scales (optional but helpful)
• Timers for station rotation

Assessment

• Formative: teacher observations during station work for correct reading of scales and correct unit recording (g vs kg).
• Formative: listening for explanations about heavier/lighter and whether comparisons use the same unit.
• Exit ticket: estimate → measure → reasonableness check, assessed against success criteria.

Differentiation

• Support for students needing scaffolding:
• Provide a unit-choice sentence starter: “I chose grams because… / I chose kilograms because…”
• Use a “1 kg benchmark” card showing 1000 g and common references (teacher-selected, age-appropriate).
• Offer a partially filled recording sheet (object names given, students fill in mass only).
• Pair students strategically (one confident reader with one developing measurer).
• For students requiring extra challenge:
• Ask them to convert for comparison (for example, if one mass is in g and the other is in kg, convert so both are in the same unit) and explain the conversion.
• For EAL learners:
• Use visual supports on the worksheet showing g/kg and “heavier/lighter.”
• Encourage oral rehearsal of sentence frames before writing.
• Safety and access:
• Ensure objects are manageable and scales are stable; assign roles (one reads, one records, one places object).

Differentiation (Extension for advanced learners)

• Advanced task option: “Weight detective—Find two objects whose masses are close.” Students must:
• measure at least two pairs of objects,
• state which unit was used,
• compare in the same unit,
• then write a justification comparing the difference (for example, “They differ by about 50 g” or “by about 0.1 kg”).
• Students can also create a “best unit” rule for their station data (e.g., “If it’s under 1000 g, we usually use g”).