This completing fact families worksheet gives 1st graders six number houses to fill in—writing two addition and two subtraction facts for each set of numbers. Answer key included for fast, no-prep math practice.

In this Subtraction as an Unknown Addend Activity, students find the unknown whole number in addition and subtraction equations up to 20.

This 1.OA.4 common core worksheet gives 1st grade students three fact families and the four related addition and subtraction facts in each, plus an answer key, so subtraction starts to feel like addition read backwards.

In this Adding and Subtracting Unknown Numbers Activity, students find the unknown whole number in addition and subtraction equations up to 20.

This fact families worksheet has 1st graders write twelve column addition and subtraction facts from three number families within 20. An answer key is included for quick, no-prep checking.

In this 1.OA.1 First Grade Common Core Lesson, students find the missing addends in equations up to 20.

In this 1.OA.4 First Grade Common Core Lesson, students practice finding the missing added using subtraction as strategy to solve.

This Thanksgiving fact families worksheet gives 1st grade students practice with addition and subtraction within 20. An answer key is included, so a holiday math review takes almost no prep.

This christmas math fact families worksheet gives 1st Grade students three number triangles and twelve facts to write. An answer key is included, so holiday fact practice needs no prep.

In this 1.OA.8 First Grade Common Core Lesson, students find the unknown whole number in addition equations up to 20.

Using Subtraction With 6-7-8-9 Differences Activity, students solve single digit subtraction equations, then sort answers into categories.

This St. Patrick's Day Fact Families Worksheet gives 1st grade students three triangles with a missing number and room to write all four related facts. An answer key is included, so it is ready to print and go.

In this Adding Two Digit Numbers Activity, students add up to four two-digit numbers using strategies based on place value and properties of operations.

Using Subtraction With 2-3-4-5 Differences Activity , students subtract single digit subtraction equations, then sort differences into categories.