As we begin to transition to a summer schedule around here, one thing we do is math on Mondays. It helps keep us in practice of what we learned throughout the course of the year.
Personally, I like to use the Kumon workbooks. (We sometimes use these for extra practice too.) They are inexpensive and are a break from our normal Abeka math textbook.
You can find several of the Kumon math workbooks here.
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