• To learn how to use a spreadsheet to enter a formula.
• To understand the use of simple algebra.

 A data projector is ideal, but a large monitor will suffice. Failing that, use an overhead projector. Have ready an OHT showing a blank spreadsheet grid. Use this to explain cell references and show how values are entered into cells.

Make copies of the activity sheet for this lesson.

If a large display is used, zoom the spreadsheet to 200%. Ask whether anyone has used a spreadsheet before. Click on cells, note what happens. In Excel, the cell reference is shown at the top left, just above the sheet. How do cell references differ from map co-ordinates? (The origin is at the top left.) Select cells and ask pupils to give the cell reference. Ask pupils to give examples of mathematical operators.

Ask the class to write down simple calculations that the spreadsheet may perform. Take an example and ask, 'How would you do that with a calculator?' On a calculator, the = sign means, 'Now work it out.' (What else does it usually mean?)

Enter values into A1 and B1. How can we get the answer in C1? Click in C1 and enter =A1+B1 (the How to... sheet gives further help).

Draw attention to the role of the cell references. The are entered by clicking on the cells containing the values. The = sign now means, 'Here is a formula - work it out.'

Repeat the process in Row 2, doing subtraction this time. Why is order so important? What happens if we put =B2-A2?

Choose children to work on available computers. The rest work on paper. Set the task to write four algorithms for addition, four for subtraction (eight in total). Record on the top half of the sheet as a normal 'sum'. On the lower half of the sheet, record each as a spreadsheet formula beginning with the = sign.

Draw the class together to look at the display. Enter some of their examples. Suggest changing the start values in A1 and A2. What do children think will happen?

On the computers, children can try changing the contents of A and B. Insist they predict the result before pressing Enter.

If time permits, ask for similar examples with multiplication and division. The computer uses * to avoid confusion with the letter x. There is no division sign on the keyboard, so / (forward slash) is used instead.

Keep the algorithms simple. Make sure that pupils can identify cell references. Try varying one thing at a time - 'We added 4 and 5. On your own, can you add 6 and 5?' Show on the computer that A1 can be clicked and the contents retyped. We have told the computer to add A1 and B1, whatever values are stored there.

The use of the = sign is difficult for many children. Talk this through - the equals sign goes in first because it means, 'Here comes a formula.'

If you are using a large display, enter and test some of the children's own formulas. Otherwise, write them on the board and ask the class what the result will be. Everyone to write three numbers in three different cells, enter a formula in the fourth cell.

Make arrangements for all pupils to use the computer before the next lesson.