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.
There are other sources for worksheets also. You can find many public schools and private schools which will provide free worksheets for you if you buy textbooks from the school.
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.
Times are different these days. Kids are growing up in a world of microwaves, fast food chains, Nintendo, Wifi, iPads, along with a ton of other technical marvels.