1. Doing practical work in groups
Estimation is an important skill in both mathematics and science and a useful skill to cultivate for all pupils. Simple balances can be made with very modest resources that allow pupils to approach measuring and estimating weight through practical investigation. You may like to make simple balances and plan and carry out these activities jointly with a science teacher in your school. This can be done by helping pupils to compare and contrast weights in different ways.
Case Study 1: Estimating weight
Mrs Nkumu in Nigeria was on a teachers’ course at her local district offices and as part of the day’s lesson on numeracy the facilitator told the following story to them. Then she asked them what they thought the girls knew and what would they do next with these pupils if they were in their class.
‘Two girls, Ranke and Ade, were discussing the quantity of popcorn in two packets, A and B which looked the same shape and size. Ronke picked up the packets one after the other and was surprised that B felt heavier than A. She told Ade that B appeared to be heavier than A. Ade decided to put the two packets in the two pans of a simple balance. (See Resource 1: Simple balance). She observed that on the scale, packet B went down and so B is heavier than A. Ronke was right.’
The teachers worked in pairs and devised activities that encouraged estimation of heavier/lighter, then using a balance or scales to test their ideas. Each pair tried their lesson out with their class and reported back next session.
Mrs Nkumu found that her class enjoyed the lesson but that she did not have enough different objects for the pupils to use. Next time she said she would spend more time collecting objects and she would use smaller groups of 4-6 rather than over 10 each.
Activity 1: Comparing weight
You will need 5 simple balances (see Resource 1) to carry out this activity and 5 sets of common objects e.g. stones, balls, tins, bottle tops etc that could be used with the balances.
Write instructions for your pupils on the board (see Resource 2: Worksheets) and show the class what you want them to do using any two objects.
Ask them to estimate which is heavier by giving the objects to 2 pupils to answer.
Now ask a pupil to test their idea out by putting them on the pan and let them decide.
Ask them which is the heaviest object and why they think so.
Organise your pupils into 5 groups, giving each group a set of objects and a balance. Ask pupils to find which object is heavier by estimating its weight and then by using the balance. (See Key Resource: Using group work in the classroom)
Ask them to fill in a table of their results to share with the class to see if everyone agrees.
You could challenge older or more able pupils to see if they can order their objects from heaviest to lightest before testing. How could they test their answers using the simple balance?