Not that I am a big advocate of workbooks, but I bought some of these for a trip we have coming up to keep S busy and thought I should let you know about this deal. School Zone workbooks are only $1.40 right now at Amazon and they are also part of the Amazon 4 for 3 promotion. If you scroll down to "Customers Who Bought This Item Also Bought" you can see other $1.40 choices. You can mix your 4 choices and get 4 of them for $4.20. Here are the ones I ordered, but there are more choices:
Dollar Tree and dollar bins at Target also carry workbooks for (obviously) $1, but I think these may be a little higher quality.