Engagement entails much more than rote repetition of a procedure. Math worksheets tend to present very similar problem types over and over, leading to mundane practice of disassociated skills. For students who understand the material and successfully complete an assignment, another worksheet becomes meaningless. On the other hand, for the students who don't understand the material, an alternative method of instruction is what's needed. Another worksheet simply adds to the student's frustration, or worse, contributes to a belief that "I'll never understand math." A cute image or a "fill_in_the_blanks" riddle does nothing to increase engagement or learning (and let's face it, those riddles are not funny!). Instead, teachers need to increase engagement by providing students with exercises in which they discover patterns and relationships, solve problems, or think creatively about math relationships.
So what's a concerned parent/teacher to do? It really requires evaluating what's available in 5th Grade Math Worksheets that have attempted to move to the next level in education and engagement. When's the last time that you wanted to spend more time doing something you hated and dreaded? Top that off with seeing no reason for the chore you so dread in the first place and you have a complete and total recipe for disaster.