Numeracy: Measuring up
22 September 2008Add to My Folder
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Use real-life contexts outside the classroom to help develop children’s measuring skills
Outside the classroom, there are countless creative opportunities for maths. Children can explore the immediate school environment to practise measurement skills that involve length, weight, capacity, volume, area, time, angles and temperature. In this article, we look at some activities for practising and consolidating measurement skills within the school grounds.
With practice, most children develop a feel for units of measurement and can often hypothesise: If we know the area of the classroom, then we can guess the size of the hall; when we know the area of the hall, we can guess the size of the playground. This sort of activity helps children to make predictions based on prior knowledge and gives them a starting point from which to build further estimations. Approximation is a key principle of measurement, and so for this reason you should promote the vocabulary of ‘about’ or ‘to the nearest unit’.
1. Estimation, guesstimation
As a first activity, go to the playground and ask the children to get into groups of six. Ask each group to stand in a line and make a friend chain, stretching their arms as far as possible so that they touch fingertips. Can they estimate how long their line is without a ruler? Score the beginning and end of the line with chalk. Then, use metre rulers to compare estimates with actual measurements and record answers to the nearest centimetre. How close were they? Give points for their answers. For example, exactly right = 100 points, within 50cm = 50 points, and so on. Now ask the children to ‘guesstimate’ the perimeter of the playground in order to assess their understanding of length. Although length is one of the simplest concepts to grasp, children will find this difficult unless they can make a direct comparison to something of a known length. Encourage them to use their friend-chain measurement as a starting point. After approximations have been made, ask for different ways of measuring the playground. Suggest measuring the perimeter of the playground using the length of their own feet as people used to do. Ask why this could cause problems. This provides a good opportunity to talk about non-standard units of measurement and what people used before rulers, tape measures and trundle wheels.
2. Trundling along
Give the children some trundle wheels to measure with. Make sure that they start in the correct position with the 0cm or 0m mark touching the ground. Remind the children to count the clicks and account for the fraction of a turn left when reaching the end of a measurement. Watch out for tight corners or areas that are difficult to measure.
Back in the classroom, tell the children that you have measured a shape in the playground that has an area of 24m squared. What might the lengths of its sides be and what could the shape be? Children might work out that the shape could be 1m x 24m, 2m x 12m, 3m x 8m and 4m x 6m. The length and width could also be decimal numbers, such as 2.4m x 10m, 3.2m x 7.5m, and so on. They will have to think hard about what these shapes look like, but it encourages a lot of thinking about different rectangles in the school grounds.
3. Two pence challenge
For the next challenge, ask the children to work out how many 2p pieces, placed in a row, it would take to measure the width of the playground. What strategies can the children think of? Would it be a good idea to physically place 2p coins across the playground? What problems can they envisage? How does it compare to another method? For example, would it be more accurate to see how many 2p coins would fit across one metre then measure the width of the playground? What would happen if you only had a 15cm ruler? From here, you could ask the children to work in groups to estimate and then calculate how long a money trail stretching from the school entrance to the classroom would be. How much money would the trail add up to if 10p pieces were used instead? Ask the children to consider how using different coins would affect the answer.
4. Measuring nature
Outdoor measurement activities give you the chance to assess the children’s knowledge and understanding of a range of ideas, and what alternative conceptions they might hold. For example, you could ask the children to find a leaf and calculate its area. It’s possible that some children might over generalise what they already know about the area of other shapes and attempt to apply it to the leaf. So, if children have learned to multiply the length by the width to find the area of a rectangle, they might try to do the same with the leaf. Discuss with the children why this approach would be wrong, and ways of solving the problem. Provide children with some 1cm grid transparencies so that they can work out the leaf’s correct area.
5. Measurement trail
There are estimation opportunities galore around the school, but some objects might not be particularly easy or safe to measure, so will need selecting carefully. Tour the school and generate a list for a measurement trail. As part of this trail, you could also estimate other objects such as the height of trees, the capacity of a litter bin and the area of a flowerbed. Another idea to try is to challenge children to find something around the school that you would measure in millimetres, centimetres, metres, grams, kilograms and litres. Measuring activities are hands-on lessons, perfect for improving children’s confidence when handling equipment, communicating using specific vocabulary, working in a team and solving problems collaboratively. Consider the sorts of skills you want your class to practise and let children step up to the mark. Given the chance, they’ll soon measure up.
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