Three Addends Problems Worksheet

Adding three numbers is the moment addition stops being a single fact and starts being a strategy. A first grader who can already add two numbers has to learn that three addends can be regrouped in any order, and that the fastest route is almost always to find the pair that makes ten first. This three addends problems worksheet builds that habit on purpose: every equation in Part A hides a make-ten pair, so children practise spotting 5 and 5, 7 and 3, or 8 and 2 before they add the leftover number. That is the thinking behind Common Core standards 1.OA.A.2 and 1.OA.C.6, and it is the foundation every later mental-math shortcut is built on.

This 1st grade addition worksheet is a two page printable with a full answer key. Part A gives six three-addend equations with a clear box for the sum. Part B flips the task around: the sum is already ten and the child writes the missing addend, which sits in a different spot in each problem so nobody can answer on autopilot. Part C finishes with a balloon word problem that puts the same skill into a real situation, complete with a picture children can count to check their thinking. Work through Part A together on the board, then let students finish Parts B and C on their own.

What’s Included

• 1 print-ready PDF worksheet
• Answer key
• 6 three-addend equations, 6 missing-addend problems that make ten, and 1 illustrated word problem

There are three reasons this three addends problems worksheet helps children learn. First, the make-ten pair is built into every problem, so students discover the strategy by using it rather than by being told about it. Second, the missing-addend section develops the idea that addition and subtraction undo each other, which is the same reasoning children will need for fact families and for algebra years later. Third, moving the blank around the equation keeps the work honest: a child has to read the whole number sentence before answering, which is exactly the flexible thinking a timed fact drill never builds.

Teachers and parents can extend the practice without any new printing. Hand out ten counters and ask children to build each Part A problem, sliding the make-ten pair together before counting on. Play a quick partner game where one child says two numbers and the other names the third number that makes ten. Roll three dice, write the addends in any order, and race to the sum. Have students draw their own balloon picture for a three-addend story and trade it with a friend to solve. A few minutes of hands-on work like this makes the written page much easier.

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