As a middle-school math teacher, I have seen many students who do understand abstract concepts, and even enjoy learning about things like Pi and the Pythagorean Theorem, but who appear to be unable to do so due to a weak grasp of math fundamentals.
How much money do I have left if I buy a soda? By the end of the week, how much of my daily allowance will I be able to save if I don't?
Thus, the math worksheets which you get for your kids should include interesting word problems that help them with the practical application of the lessons they learn. It should also present the same problem in a variety of ways to ensure that a child's grasp of a subject is deeper and comprehensive.
Homeschool worksheets fortunately will not over-tax your budget. There are many places where you can get them at extremely low costs. In fact, several websites offer printable worksheets for free.
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