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Grade 1 Math  ›  Addition & Subtraction  ›  Lesson 14 Grade 1 Math - Addition and Subtraction Missing Numbers & Unknowns Learn how to find missing numbers and unknowns in first grade addition and subtraction equations. Students practice missing addends, unknown totals, unknown differences, and unknown starting numbers within 20. This lesson builds directly on understanding the equal sign: the missing number must make both sides of the equation have the same value. Use counting on, fact families, part-part-whole thinking, and the relationship between addition and subtraction to solve. Missing numbers Unknown addends Addition within 20 Subtraction within 20 Grade 1 algebraic thinking 🎯 What You Will Learn Find an unknown in different positions The missing number can be a...

Grade 1 Math  ›  Addition & Subtraction  ›  Lesson 13 Grade 1 Math - Addition and Subtraction Equal Sign and True/False Equations Learn what the equal sign really means and decide whether addition and subtraction equations are true or false by comparing the value on each side. This first grade math lesson shows that the equal sign means “the same value as,” not “the answer comes next.” Students practice equations with totals on either side and expressions on both sides. Equal sign meaning True and false equations Addition equations Subtraction equations Grade 1 algebraic thinking 🎯 What You Will Learn Understand the equal sign Know that = means the value on one side is the same as the value on the other side. Check both sides Find the value of each side before de...

Grade 1 Math  ›  Addition & Subtraction  ›  Lesson 12 Grade 1 Math - Addition and Subtraction Fact Families: Addition and Subtraction Learn how the same three numbers can make related addition and subtraction facts. Use parts and a whole to build fact families and connect addition to subtraction. This first grade math lesson uses fact families, part-part-whole models, and related addition and subtraction equations to help students recognize number relationships and use known facts to solve new problems. Fact families Related facts Addition and subtraction Parts and whole Grade 1 math 🎯 What You Will Learn Find the parts and whole Recognize which two numbers combine to make the whole. Build related facts Use the same three numbers in addi...