Solve vertical and horizontal computation problems
How many kids in school have done their homework? Again this can be answered in several ways: in percentages, 70%; or in ratio, 7:10; Both of these mean out of ten kids in class there are seven good ones who did and three not-so-good ones who didn't. The bottom line is that kids learn math much better when it makes sense.
Subtract 1- or 2-digit number from a 2-digit number with/without renaming
They're also available for nearly all grade levels. There are printable middle school, high school, elementary school, and even pre-school worksheets.