There are many free worksheets available, especially online, but still the best worksheet is one that you personally draft. This way, you are able to match the level of difficulty of the activity in accordance to the performance level of your own students. It is not bad to reuse worksheets for another batch of students, but once in a while it is also better to vary the activities you give to kids. Worksheets can be made for fun if it is attuned to the current interests of kids. The kids will respond better to activities close to their own interests.
Maths worksheets should challenge students and at the same time should not be a scary subject to attempt. Worksheets are a recommended mathematic learning source and an amalgam of the total syllabi. They are the top priority in the education system and are used as a learning tool by many parents, schools, teachers and students.