I will admit that there is one type of worksheet that I used in the past and found relatively beneficial, although it had a different kind of flaw. For my Basic Math, Pre_Algebra, and Algebra classes, I had several books of "self_checking" worksheets. These worksheets had puns or puzzle questions at the top, and as the students worked the problems they were given some kind of code for choosing a letter to match that answer. If they worked the problems correctly, the letters eventually answered the pun or riddle. Students enjoyed these worksheets, but there are a couple problem areas even with these worksheets. Some students would get the answer to the riddle early and then work backward from letter to problem answer, so they weren't learning or practicing anything.
Math worksheets don't promote critical thinking _ Math worksheets rarely ask students to think critically or creatively. They usually present multiple examples of the same problem type with the hope of reinforcing a skill or procedure. They do not challenge students to use higher order thinking skills such as comparing, analyzing, deducing, and synthesizing. These skills are built through activities in which students discover concepts, explore ideas, test a hypothesis, solve a problem, and discuss their thinking with their peers. Exploring concepts and problems in many different ways builds interest and promotes critical thinking.