David Watkins has provided an extensive, easily searchable collection of Excel Mathematics worksheets on dynamicmaths.co.uk. As you can see from the above image (his Algebra-01 sheet on simplifying linear expressions), these worksheets can be customised to suit a particular class. As well as a class activity, these could make excellent starters or plenaries, I think they would also be useful for student self-study / revision.

For another excellent collection of spreadsheets investigate the resources on Mike Hadden’s MathsFiles site.