In other words, they never memorized their multiplication tables! Many times I have seen a student do poorly due to a weakness in basic math facts they should have learned in third grade.
Therefore creativity is a must for worksheets to be successful : Regardless if you are trying to review math, science, reading, writing, health, or social studies, your goal should always be to try and create something that will generate desire in the students to actually want to do it. If you can do this, the battle is practically over already.
You can find worksheets for a wide range of courses--almost any course you want to teach your children. These include spelling, writing, English, history, math, music, geography, and others.
There are several standard exercises which train students to convert percentages, decimals and fractions. Converting percentage to decimals for example is actually as simple as moving the decimal point two places to the left and losing the percent sign "%." Thus 89% is equal to 0.89. Expressed in fraction, that would be 89/100. When you drill kids to do this often enough, they learn to do conversion almost instinctively.