Book excerpt: Motivate your students to break out of their "fog" and focus on problem solving and learning with these 30 medium-level brainteasers. They will challenge students and help them develop their critical-thinking skills. Puzzles range from riddles and secret codes to patterns and math problems. Each BrainStarter requires very little time and no setup, making them easy to incorporate into your daily plans. You can also try them with the entire class or as quick team-building exercises.