4
Choose the best tool
Learner’s Book 1: Unit 12, pp. 176–177
GoalChoose the right instrument to measure length, mass, capacity or temperature.
New words
compare · look at two things to see how they are differentright tool · the instrument that fits what you measure
Explanation
To measure well, first ask: what do I want to find out? If it is how long, use a ruler. If it is how heavy, use balance scales. If it is how much a container holds, use a measuring jug. If it is how hot or cold, use a thermometer. With balance scales we can also compare two things. Here the lorry’s pan goes down, so the lorry is heavier than the bike.
Worked examples
| job | tool |
|---|---|
| height of a sunflower | ruler |
| mass of a melon | scales |
| capacity of a teapot | measuring jug |
| how warm the room is | thermometer |
A kitten and a puppy are on the scales. The right pan goes down, so the puppy is heavier than the kitten.
To find the capacity of a bottle, pour the water from the bottle into a measuring jug and read the number.
Class activity
Match game: write or draw 4 jobs on cards (how long is a rope, how heavy is a pumpkin, how much water fills a pot, how hot is the day) and 4 tools on other cards. Match each job to the right tool. Race a partner!
Practice
1
Which tool measures how long a skipping rope is?
a ruler (or a tape measure)
2
Which tool would you use to find how heavy a bag of potatoes is?
balance scales
3
Which is lighter, the fly or the cat?
the fly
4
What does each tool measure?
| tool | what it measures |
|---|---|
| thermometer | ? |
| ruler | ? |
thermometer: temperature; ruler: length