These worksheets by ArgoPrep will have first-graders completing addition problems with a missing addend sum under 10. These worksheets will have students learning early algebraic skills with using inverse operations to find the answer of these problems. These aren't your standard addition problems and students will be challenged in their understanding by discovering the missing addend. Students will complete problems like 5+ __=10, or __+3=7. These worksheets will help students learn and practice new strategies.