3. Assessing understanding of length

It is important that pupils have a real-life ‘feel’ of what different lengths mean and are able to estimate and measure the length or height of an object. This is a very useful skill in real life. For example, will a tree fall on our house if it is chopped or falls down? To assess whether they have this ‘feel’, you can use a question to solve on paper that requires them to use their understanding or give them a final investigation about a real object, such as that in the Key Activity.

When the task is complete, encourage your pupils to find out more about the indigenous trees of your country and have a go at measuring a large tree near your school if there is one. Working in this practical way will build their confidence in dealing with length.

Case Study 3: Assessing understanding of length

Mrs Chamwala from Mongu wanted to find out if her pupils had a real understanding of different lengths, so she designed a paper activity that they had to do individually to assess this. She copied the activity onto the board (see Resource 3: Question on length). She asked her pupils, who were Grade 6, to work on their own and think carefully about the answers before they filled in the gaps. She collected their books and looked at their answers.

Mrs Chamwala realised that many of her pupils had not got a real feel for length yet and so she decided to do more practical activities. She asked them to measure the school grounds but they had to estimate the length of each side first and record this. Each group took it in turns to do the measuring as she only had one long tape. She had made a large table of the key measurements and each group put in their measurements as they finished. She did not display this until all groups had finished so they would not be influenced by others’ results. (She planned to use this data later for a geography lesson to produce a scale map of the school site.)

When all pupils had completed the measuring, she discussed the variations in their measurements with them and then asked them why this was so. They were able to suggest some good reasons such as starting at different points and not holding the tape straight. She was pleased at how they saw the purpose for understanding measure.

Key Activity: How big is the baobab tree?

Read Resource 4: Baobab tree before you plan for the lesson, but think how you might adapt this to your pupils’ needs. You will need to find a very long tape measure.

If possible, take your pupils outside to where there is a lot of space; otherwise, use a large hall to try out the activities. You will also need about 20 pupils of average 1 m height and so you may decide to combine with another class. Work with the whole class together and ask guiding questions to help them solve the problem.

Show the picture in Resource 4 to the class and read the following extract about the baobab tree to the class.

‘In South Luangwa National Park there is a 1,000-year-old baobab tree, known as the kondanamwali. It is about 20 m high and has a circumference of 8 m.’

When you have finished outside, bring your pupils inside and ask them to answer the questions in Resource 4 to assess their understanding.

Next lesson, ask them to make a display of all their measuring activities and invite other classes to come and see their work.

2. Letting pupils plan their investigations

Resource 1: Sample questions