1 Accident prone
- To get a more accurate estimate of the length of an average sized car, students could measure cars in the school car park.
- To get a reasonably accurate measure of the distance between two cars in a queue, students could observe cars queued at lights.
- To find how many cars are in the queue students will need to divide the total length of the queue by the combined length of one car and the distance between two cars.
- Students will need to ensure that all units are the same when adding, multiplying and dividing.
2 Coin trail
- Students should discuss the best way to get an accurate measure of the thickness of a 10 cent coin. (Measuring ten coins for example and dividing the answer by 10.)
3 Grandad left me a choice
- Students should discuss the best way to measure 2 kg of coins and a metre long trail as they will probably have insufficient $1 coins to make a 2 kg or 1 metre.
Teaching ideas
Getting started (Getting started sheet 11)
This link displays the Getting started on page 185 to use as a class discussion.- What do you know?
Divide the class into two groups and get them to have a race to write down all the metric conversions they know. Give an example first of how to write these. For example, 1 km = 1000 m. NOTE: this is not assumed knowledge but some students may know these. 
10, 100 and 1000 Follow me (Teacher resource sheet 25)- This link displays Follow me cards for you to print and cut up (and laminate). One student starts by reading what is written on their card. You might need to revise multiplication and division by 10, 100 and 1000 using the Follow me cards given on the CD ROM.
- Support – get students to use a place value chart to help play the Follow me game and use digit cards to move the digits along.
- Extension – Play the Follow me game, as described above, on a “how fast can we do this” basis.
Should the answer be bigger or smaller?
- Use the Discussion on page 188 as a class discussion.
- Before beginning the “Converting smaller to larger units” section you could use the Discussion on page 190 as a starter.
Teacher notes
- It is best if students are able to work out whether to multiply or divide using common sense rather than using an algorithm. Get them to think about the units they are converting between and decide if the answer will be bigger or smaller than the number they start with. Students can use the prefixes and place value charts to help them decide what to multiply or divide by.
- You could use equipment such as base 10 materials to represent the units. For example 1 litre could be represented by a thousands block showing how this “converts” to 1000 small millilitre blocks and so on.
- Students must be able to multiply and divide whole numbers by 10, 100 and 1000.
- Encourage students to think about a suitable numeracy strategy to help work out the answers to Activities 1 and 2. You could choose some of the problems for them to think, pair and share and then report to the class at the end of the lesson which strategy they decided was the most efficient.
