1. Thinking about measurement in groups
Practical work has many purposes. It might be to learn a particular skill, or to help motivation and enjoyment. It can also be used to promote higher-order thinking skills and to encourage students to talk about science and communicate their ideas in a variety of ways. Resource 2 contains some general information about organising practical work. In the first activity, you will use the apparatus as a stimulus to promote thinking and talking. There is an opportunity for you to question students in groups while they are working and for you to target your questions at a level suitable for that group.
Case study 1: How will you organise groups?
Mrs Egwali gathered the basic instruments that were available in the school lab. She also borrowed some micrometer screw gauges from a neighbouring school. Previously she had asked the students to bring any measuring instrument that they could get from home and something that could be measured with their instrument. They bought things like tape measures, measuring jugs and simple scales. Mrs Egwali put the measuring instruments and some objects to be measured on the table. She also cut cards from manila paper and placed them on the table. She divided the students into groups of five. Each group had to work as fast as possible and follow a set of instructions:
- Pick one instrument and discuss its correct name among the group.
- Write the name on the card.
- Pick up the object it can measure accurately and write its name on the card.
- Place the cards next to the instrument and what it measures.
Mrs Egwali walked around while the students worked. They were actively involved except for two groups in which some students were quite passive. She reorganised the two groups and put the passive students together. It pleased her to note that when they were put together they became more involved. She realised that this was because their abilities were similar and they felt more confident. Before the lesson ended, she noted that no group had picked the micrometer. She demonstrated to them how it works and this led to a discussion about which instruments were the most accurate. Joshua had bought a spoon and a bag of sugar. Mary said that that wasn’t a very accurate way of measuring but Joshua said his mother’s cake was always perfect! Mrs Egwali explained that in science it was important to make accurate measurements. Some of the instruments had been given various names, so she asked students to choose the correct one.
Activity 1: Getting started with measurement
Before the activity gather as many pieces of measuring equipment as you can at the front of the class. Gather the students round the table and ask them to name as many pieces of equipment as they can.
Divide the class into groups and ask each group to work out what they think the instruments might be used for. (Resource 3 has some ideas of equipment you could use and questions you could ask while they are working.)
Ask the groups to report back. While they are working go round and ask some leading questions to help the students to work out the uses. If you have something like a micrometer, see if they can work out how to use it before you explain to them. Get them to think about when it might be used.
Ask each group to measure the length of an exercise book to the nearest millimeter. Collect all the measurements on the board. You will find some variation! Look at the list. Are there any readings you could reject as they are clearly inaccurate? What is the average? What is the range? Use these results to explain that it is important for scientists to measure things carefully.
After the activity, reflect on how you divided up the students. Did each group have questions of an appropriate level? Was it easy to decide who to put in what group? Do you always let them work with their friends?