Help your students practice addition and subtractions, sharpen their logic skills, and strengthen their problem-solving abilities with these Addition Grid puzzles. There are ten different sets. Each set contains an EXPERT level puzzle, an ACE level puzzle, a NOVICE level puzzle and an answer key.These puzzles are perfect for early finishers, homework, centers, cooperative learning, extra credit, and even times when you need a fun but educational activity at the end of the week. Because they reinforce basic skills and have simple instructions, they are suitable for many grade levels, and students of varying degrees of English fluency. The Novice, Ace, and Expert levels help you differentiate for the variety of abilities in your classroom.In addition to practice with basic number facts, the puzzles also encourage development of skills needed for algebraic thinking, such as thinking backward, solving for an unknown, and eliminating solutions.