Addition Within 20 Error Analysis Worksheets helps students build number sense by identifying, analyzing, and correcting common addition mistakes. Designed for Grade 1 and Grade 2 math instruction, this resource encourages critical thinking, math reasoning, and self-checking while reviewing addition facts within 20.• Includes 13 worksheets and answer keys• Covers true or false, missing addends, number lines, ten frames, word problems, mixed review, and challenge review activities• Supports error