The Power of Autonomy
Students are far more motivated when they have a choice. Instead of printing the exact same worksheet for everyone, print three different collections (e.g., Sports, Animals, Technology). Tell students: "You must complete one scramble sheet, but you get to choose which topic." The mere act of choosing increases engagement dramatically.
Competence and the Danger of Over-Challenging
Intrinsic motivation dies when a learner feels incompetent. If you notice a student consistently giving up, you have misjudged the difficulty. It is always better to err on the side of 'too easy' to build momentum, and only increase the difficulty once the student is actively seeking a tougher challenge.
Visual Tracking Over Material Rewards
Do not offer candy or extra recess for completing puzzles. This communicates that the puzzle is a chore to be suffered through for a reward. Instead, use visual tracking. The digital Daily Challenge uses 'streaks'—a powerful psychological tool. Replicate this with a sticker chart or a 'Word Wizard' board where progress is highly visible but purely intrinsic.