• To be able to collect a range of real data.
• To be able to make sensible judgements about data accuracy.

Download and make copies of the recording sheet for this lesson. NB the sheet has 6 columns for recording. If more are required, open the document in Word. Select a column, and insert a column from the Tables menu.

Measuring equipment will be needed: metre sticks, rulers, tapes, personal balance, cm squared paper (for hand area), height gauge or tape stuck to a wall, etc.

Ask questions to ascertain children's understanding of the vocabulary of measurement. What is a circumference? How can we measure the circumference of various items? How can we measure more accurately?

Ask quick-fire questions to compare measurements: "Jane's hand span is 13 cm. Tom's is 12.5 cm. What is the difference?"

Explain that we are going to collect personal measurements. There are many possibilities, and they can be agreed with the class. Refer to the discussion at the end of the previous lesson.

Stress that the data is personal and we should always ask the person's consent before using it. Some children are sensitive about their weight, and it may be wise to leave this out. Foot length, hand span, arm span, arm length, stride and head circumference could be measured. A "fair test" of strength can be devised, involving pressing on a personal balance.

It is very important to clarify what we are going to measure. This is especially true for stride - some children will try to do the splits!

Should we be exact with measurements, or round to the nearest unit? For example, should we measure hand span to the nearest millimetre, half centimetre or centimetre? How accurate are the measuring instruments?

Agree the units to be used. Distribute the sheet. Column headings need to be filled in.

Work in pairs to measure and record each other first. Measure and record other pairs if time permits. Exchange data so each has his/her own copy of all the class data. (Note that each pair's will be in a different order.)

Ask the children to record their data on a master sheet to be kept as a teacher's copy.

Ask, "Did you measure anyone else, as well as your partner? Do your measurements agree with theirs?" Cross-check with other pupils' measurements of the same child. If there are discrepancies, measure again - how might the error have occurred?

Are there connections in the data - for example, between hand span and hand area? The computer will help, because it can sort data into numerical order.