Measuring with Metric Units: a week of ready-to-teach maths

Five days of lessons for Year 3 Measurement. Print this pack and the week is prepared: each day has a one-page plan and a student worksheet, plus item cards, claim cards, a mini-check and every answer.

Start here: five minutes to Monday

1. Skim the week at a glance on the next page.
2. Print the five days. Each day is two A4 sheets: a plan and a worksheet.
3. Cut out the item cards and the claim cards once; they are reused all week.
4. Open the free interactive unit on your board. Every plan tells you which picture to show and which buttons to press.
5. Teach straight from the plan. Timings, talk prompts, misconceptions and answers are all on the one page.

No maths background needed

This pack is written for the busy generalist teacher. Length is how long or tall (centimetres and metres), mass is how heavy (grams and kilograms), and capacity is how much a container holds (millilitres and litres). Children learn which unit suits an everyday thing, and estimate with benchmarks they can carry or picture: a fingernail is about 1 cm, a big step about 1 m.

One day, one lesson

The five lessons fill a week of maths, one lesson of about 50 minutes a day. Run them in order: each day stands on the one before. Every plan marks a split point if your timetable runs two shorter sessions.

The week at a glance

One lesson a day for a week. Each day stands on the day before, so run them in order.

How the week builds

Days 1 and 2 are about choosing: which quantity, which unit, which tool. Day 3 gives children benchmarks, and Days 4 and 5 put them to work, first to estimate and then to judge other people’s claims. It leans on the Year 2 measuring unit (AC9M2M01) and on Numbers Beyond 10 000 (AC9M3N01).

Materials for the week (one trip)

• From the classroom: scissors, pencils, 30 cm rulers, a metre ruler or tape measure, this pack printed.
• Kitchen scales, a measuring jug, a 1 L bottle of water and a 1 kg bag of rice or flour.
• A box of paperclips (small ones are about 1 g each) and a tray of things to estimate.
• Cut out once, use all week: the item cards and the claim cards in this pack.

Words for the word wall

length, mass, capacity, centimetre (cm), metre (m), millimetre (mm), kilometre (km), gram (g), kilogram (kg), millilitre (mL), litre (L), benchmark, estimate, measure, reasonable

Dear families

This week in maths, Year 3 is learning which metric units measure everyday things, and how to make sensible estimates using sizes they already know.

Try this at home

• Read the labels in the kitchen: is the number grams, kilograms, millilitres or litres?
• Ask whether a thing is long, heavy or holds a lot, and which unit you would use.
• Estimate first, then measure: how many big steps across the lounge room? How long is a spoon?
• Have fun with silly claims: is the fridge 2 cm tall? How tall is it really?

Our estimates this week

Fill one row a day: a thing at home, your estimate, and the measurement.

Printed from the free seegongsik Measuring with Metric Units teaching pack · seegongsik.com/au/y3/measurement/AC9M3M01/pack

Length, mass or capacity?

Every measurement starts by naming the quantity. How long or tall is it? That is length, in centimetres or metres. How heavy is it? That is mass, in grams or kilograms. How much does it hold? That is capacity, in millilitres or litres.

We are learning to

• decide whether a question is about length, mass or capacity,
• name the metric units for each (cm and m; g and kg; mL and L),
• choose the tool that measures it (a ruler or tape, scales, a measuring jug).

Success criteria

• I can say whether something is a length, a mass or a capacity.
• I can name a metric unit and a tool for it.

You need

A ruler, kitchen scales, a measuring jug and a water bottle to show. The item cards (cut-out sheet 1), one set per group. The worksheet.

Lesson flow (about 50 minutes)

Two half-sessions instead? Split after the card sort; start Session B with the worksheet.

Watch for these ideas

• Thinking a big thing is about mass when the question asks how long. Read the question word.
• Measuring capacity with a ruler (the bottle is 20 cm, so it holds 20). Capacity is in mL or L.
• Mixing unit families (an apple of 150 cm). Grams go with mass, centimetres with length.

Answers

• the length of a skipping rope: length, metres, a tape measure; the mass of a watermelon: mass, kilograms, scales; the water in a bath: capacity, litres, a bucket or jug; the height of a chair: length, centimetres, a ruler or tape.
• the mass of a pencil case: mass, grams, scales; the juice in a small juice box: capacity, millilitres, a measuring jug; the width of a book: length, centimetres, a ruler; the mass of a cat: mass, kilograms, scales.
• Item cards: the sort is in the cut-out teacher note. Other sensible tools are fine.

Length, mass or capacity?

For each thing, write the quantity, a metric unit and a tool you would measure it with.

Your own

Find one thing in the room for each quantity.

Length: ______________________   Mass: ______________________   Capacity: ______________________

Big unit or small unit?

Each quantity has small and big units: centimetres and metres, grams and kilograms, millilitres and litres. Pick the one that gives a sensible number: a finger is about 6 centimetres, and a door is about 2 metres. The bigger the unit, the fewer of it you need.

We are learning to

• order the units in each family from smallest to biggest (the unit ladder),
• choose the unit that gives a sensible number for a thing,
• explain why a bigger unit gives a smaller number for the same thing.

Success criteria

• I can choose a small or a big unit to suit the thing.
• I can order units from smallest to biggest.

You need

A 30 cm ruler, a metre ruler, a 1 kg bag of rice and a 1 L jug. Unit cards made on scrap paper. The worksheet.

Lesson flow (about 50 minutes)

Two half-sessions instead? Split after Big unit or small unit?; start Session B with The unit ladder.

Watch for these ideas

• Using the unit they know best for everything. Ask: will the number be sensible?
• Thinking a bigger unit gives a bigger number. The bigger the unit, the fewer you need.
• Putting kilometres on the mass ladder. Kilometre is length; kilogram is mass.

Answers

• Sensible units: the length of a pencil cm; the height of a tree m; the mass of a dog kg; the mass of a coin g; the water in a fish tank L; a teaspoon of honey mL; the distance to the next town km; the thickness of a coin mm.
• Ladders: length: millimetre, centimetre, metre, kilometre; mass: gram, kilogram; capacity: millilitre, litre.
• Explain: both can be right, because a metre is 100 centimetres; 9 metres is the easier number.

Big unit or small unit?

Circle the sensible unit

Build the ladders

Write each family of units in order, smallest first.

length: metre, millimetre, kilometre, centimetre  →  ______________________________________

mass: kilogram, gram  →  ______________________________________

capacity: litre, millilitre  →  ______________________________________

Explain

A metre ruler has 100 centimetres on it.

Ben says the classroom is about 9 metres long. Mia says it is about 900 centimetres long. Could they both be right? Which number is easier to use?

The benchmark body

Benchmarks are known sizes you can carry or picture: a fingernail is about 1 cm across, a big step about 1 m, a small paperclip about 1 g, and a large water bottle about 1 L. With a benchmark, an estimate is a reasoned answer, not a guess.

We are learning to

• find body benchmarks for 1 cm and 1 m,
• feel benchmarks for 1 g and 1 kg, and see one for 1 L,
• use a benchmark to estimate a length, a mass or a capacity.

Success criteria

• I can show a benchmark for 1 cm, 1 m, 1 g, 1 kg and 1 L.
• I can use a benchmark to estimate.

You need

Rulers and a metre ruler, paperclips, a 1 kg bag of rice or flour, a 1 L bottle of water. The worksheet.

Lesson flow (about 50 minutes)

Two half-sessions instead? Split after My benchmarks; start Session B with the estimates and the hunt.

Watch for these ideas

• Thinking a benchmark must be exact. About 1 cm is close enough to estimate with.
• Confusing size with mass (a big pillow must be heavy). Mass is how heavy, not how big.
• Using the wrong kind of benchmark (a step to estimate a mass). Match it to the quantity.

Answers

• Benchmarks: any sensible ones, such as a fingernail, a big step, a paperclip, the rice bag and a large drink bottle.
• Estimates (any close answer is good): the width of your desk, using a big step, about 1 m; the length of a crayon, using fingernail widths, about 9 cm; the mass of a dictionary, using the 1 kg bag of rice, about 1 kg; the water in a bucket, using the 1 L bottle, about 10 L.
• Hunt: for example a fingernail or a sultana for 1 cm; a door width or a desk for 1 m; a dictionary for 1 kg; a large bottle for 1 L.

The benchmark body

My benchmarks

Estimate with a benchmark

Think about it

Why is a big step a better benchmark for the length of the classroom than a fingernail? ______________________________________________

Estimate then measure

Estimate first, then measure to check. Use a benchmark: a new pencil is a bit more than half a 30 cm ruler, so about 18 cm; a slice of bread is about thirty paperclips, so about 30 g. Then measure and see how close you were.

We are learning to

• estimate a length, a mass or a capacity from a benchmark,
• measure to check, with a ruler, scales or a measuring jug,
• say how close the estimate was and use that for the next one.

Success criteria

• I can estimate before I measure.
• I can say how close my estimate was.

You need

Rulers, kitchen scales, a measuring jug and six stations with the things on the worksheet. The worksheet.

Lesson flow (about 50 minutes)

Two half-sessions instead? Split after three stations; start Session B with the other three.

Watch for these ideas

• Measuring first and writing that as the estimate. The estimate always comes first.
• Starting the ruler at 1 instead of 0. Line the end of the thing up with 0.
• Thinking a far-off estimate is a fail. Say how far off it was and use it next time.

Answers

• Measurements vary. Check that each estimate came before its measurement and that the unit fits the quantity.
• Typical sizes: a reading book about 20 to 30 cm; a glue stick about 8 to 12 cm; an apple about 150 g; a cup of water about 250 mL; a shoe about 20 cm; a full drink bottle about 1 kg for a 1 L bottle.
• How close: the difference between the estimate and the measurement; smaller is closer.

Estimate then measure

Estimate first and write it down. Then measure. Then work out how close you were.

Closer each time

One more thing: ______________________   Estimate: ______   Measured: ______

Was this estimate closer than your first one? Why? ______________________________________

Reasonable or silly?

A benchmark lets you judge a claim. “A door is about 2 m tall” is two big steps, so it is reasonable; “a pencil is about 2 m long” would be taller than the door, so it is silly. Check the number and the unit together.

We are learning to

• judge whether a measurement claim is reasonable, using a benchmark,
• spot a claim with the wrong unit or a silly number,
• fix a silly claim with a sensible number and unit.

Success criteria

• I can tell a reasonable claim from a silly one.
• I can fix a silly claim.

You need

The claim cards (cut-out sheet 2), one set per pair. The worksheet. The unit’s self-check quiz.

Lesson flow (about 50 minutes)

Two half-sessions instead? Split after the card sort; start Session B with the worksheet and the quiz.

Watch for these ideas

• Judging by the number alone (2 is small, so a 2 m pencil is fine). Read the number with its unit.
• Calling every big number silly (an apple of 150 g). 150 paperclips is about right.
• Fixing a claim by changing the thing. Keep the thing; change the number or the unit.

Answers

• Reasonable: A classroom is about 8 m long; A bath holds about 150 L; A pencil case is about 25 cm long; A teacher is about 170 cm tall.
• Silly, with a fix: A cat has a mass of about 4 g (about 4 kg); A bucket holds about 10 mL (about 10 L); A banana has a mass of about 2 kg (about 120 g); The school oval is about 100 cm long (about 100 m).
• Claim cards: the sort is in the cut-out teacher note.

Reasonable or silly?

Use a benchmark to judge each claim. If it is silly, fix it: keep the thing, change the number or the unit.

Make your own

Write one reasonable claim and one silly claim about something in your classroom.

Reasonable: ______________________________________________

Silly: ______________________________________________

Item cards

Cut out the sixteen cards. On Day 1, groups sort them into length, mass and capacity. On Day 2, they write the sensible unit on the back of each card.

Teacher note, the sort and the sensible unit: length: the height of a door (m), the length of a crayon (cm), the distance to the library (m), the width of a book (cm), the length of a swimming pool (m); mass: the mass of a watermelon (kg), the mass of a sultana (g), the mass of a school bag (kg), the mass of a letter (g), the mass of a dog (kg), the mass of a pencil (g); capacity: the water in a bucket (L), the milk in a cup (mL), the juice in a carton (mL or L), a spoon of medicine (mL), the water in a swimming pool (L).

Claim cards

Cut out the twelve cards. On Day 5, pairs sort them into reasonable and silly, then fix each silly claim by changing its number or its unit.

Teacher note. Reasonable: A bike is about 1 m tall; A door is about 90 cm wide; A loaf of bread has a mass of about 700 g; A kitchen sink holds about 20 L; A teaspoon holds about 5 mL; A dog has a mass of about 20 kg. Silly: A pencil is about 18 m long (about 18 cm); An apple has a mass of about 150 kg (about 150 g); A drink bottle holds about 600 L (about 600 mL); A classroom is about 10 cm long (about 10 m); A cat is about 40 m long (about 40 cm); A fish tank holds about 40 mL (about 40 L).

What we know: Measuring with Metric Units

Work on your own.

1. Length, mass or capacity? The water in a jug: ______   The height of a chair: ______   The mass of a melon: ______
2. Circle the best unit. The mass of a dog: g / kg    A spoon of medicine: mL / L
3. Put in order, smallest first: metre, millimetre, kilometre, centimetre. ______________________________
4. Name a benchmark for about 1 metre: ______________________
5. A small paperclip is about 1 g. About how heavy are 50 paperclips? ______
6. A new pencil is about 18 cm long. About how long are two pencils end to end? ______
7. Reasonable or silly? “A school bag has a mass of about 3 kg.” ______
8. Fix this silly claim: “A cup holds about 3 L.” ______________________

Answers and marking guide

Answers

1. Capacity; length; mass.
2. kg; mL.
3. Millimetre, centimetre, metre, kilometre.
4. A big step (or a metre ruler, or the width of a door, which is a bit less).
5. About 50 g.
6. About 36 cm.
7. Reasonable.
8. About 300 mL (anything from about 200 to 400 mL is sensible).

A quick three-level guide

Eight questions, three ideas. Mark an estimate right when it is sensible; a child at standard can say which benchmark they used.

Weekly class record

Jot a tick as you move around the room; the mini-check fills any gaps. A tick a day is plenty.

The five columns are the five days: naming the quantity, choosing the unit, benchmarks, estimating, and judging claims.