These pieces were part of a book of math games and activities that I purchased. However, it would be very easy to make these same pieces at home using pictures of clocks from math workbooks.
The children PLAY with these rather than do pages of workbook drill. I set out the card pairs I want them to drill for the day and they match them up. They often ask for more cards to do after I have checked their matches....how often do you get that with workbooks????
TIP: These could easily be made self-correcting by simply putting matching letters on the back of pairs.