Protecting the Worksheet

When the Worksheet is given to the pupils, it would be useful if they were allowed to only have access to the cells in which they are to enter answers. Moreover, it wouldn't take them long to realise that Selecting any of the check cells would display the formulae (and therefore the correct answer) in the formula bar! Therefore, you need to do two things - set cell protection for all cells except the answer cells and hide the formula for the check cells.

Method

Highlight all the Check cells by dragging across them, then Select Format>Cells... from the menu. Look at the tabs across the top of the dialogue and Select the tab marked Protection. Note that there are two options here - Locked and Hidden: Select both options. Now highlight all the other cells except the Answer cells and Select Locked from the Format>Cells...Protection menu. If you read the information at the bottom of the Protection dialogue box, you will have noticed that protecting cells in this way will have no effect unless the worksheet as a whole is protected. Finally, Select all the Answer cells, Select the Format>Cells...Protection menu and de-select Locked.

To protect the worksheet, Select Tools>Protection>Protect Sheet... from the menu. Select all three choices and (optionally) enter a password*. Take care with your password because if you forget it, you will never be able to unlock the worksheet! You have been warned! Note that if you choose to use a password, you will be asked to re-enter it. Confirm that you cannot edit the locked cells or view the formulae in the Check cells before saving the file.

If you need to edit any of the cells you have protected, you will need to unprotect the worksheet. Select Tools>Protection>Unprotect Sheet... and enter your password (if you set one). Don't forget to protect the sheet again after editing, then save the file.

*If you protect the worksheet without a password, it is a simple matter for anyone to unprotect the worksheet at any time.