Pencil Puzzle Mysteries are a great classroom activity.
Puzzles have 3 different skill levels. The precision and patience required to complete a puzzle increases with the skill level. They work very well for developing concentration, pattern matching, memory, eye control, hand/finger control, positive/negative visual relationships and graphing.
If you have students who are rushers or sloppy, these puzzles give immediate feedback to encourage students to check their work, be neat and accu