Addition with Regrouping Game: Addition Build
Addition Build makes regrouping visual. Both numbers are built from base-ten blocks, and when the ones add up to 10 or more, students loop 10 ones and they SNAP together into a ten.
It's a digital game for grades 1 to 4 that practises two-digit addition with and without regrouping, three-digit addition with regrouping into tens and hundreds, and the place value idea underneath it all: 10 ones make 1 ten, and 10 tens make 1 hundred.
Watch it in action
The game plays in any web browser. There's nothing to print, cut or laminate, and students don't need logins.
How it works
Both numbers on a place-value mat
Each problem is laid out on a place-value mat with one row per number: 38 in the top row and 45 in the bottom row, each in hundreds, tens and ones columns. Students can see both numbers before they are put together, and the tens are grouped in fives so they are quick to count.
Too many ones? Make a ten
Put together, 38 + 45 has 8 ones and 5 ones: 13 ones. That's too many for the ones place. To make a ten, students draw a loop around ones to pick a whole row at once, or tap them one by one.
A counter keeps track: 9 of 10 ones picked. If they pick too many, the game says so: That's 12. A ten is exactly 10 ones.
SNAP! 10 ones make a ten
The moment the tenth one is picked, the ones fly into a stack in the tens column and SNAP into a single ten rod.
Now 38 + 45 is 8 tens and 3 ones, and the total is easy to read: 83. Students watched the regrouping happen, so "carry the one" stops being a rule to memorise.
Count, check and celebrate
Students count the total, type it and check. A right answer gets a cheer from the builder crew, a different celebration each time, and a crane adds a floor to the tower at the top of the screen. Five floors finish the level.
The game waits for a Next tap, so there's time to talk about the problem. A wrong answer resets the blocks to try again, and Reset starts the problem over at any time. Students who already know the answer can type it straight away, without using the blocks.
3 levels
- Level 1, Tens & Ones: two-digit plus two-digit, totals up to 69. Most problems need a ten made, but some don't, so students decide whether regrouping is needed.
- Level 2, Make a Ten!: two-digit plus two-digit, totals from 50 to 99. Every problem needs a ten made.
- Level 3, Hundreds: three-digit plus two- or three-digit, totals up to 899. Students make a ten, a hundred, or both.
Level 3: 10 tens make a hundred
In 368 + 257, the ones make a ten first. Then the tens add up to 12, so students loop 10 tens and they snap together into a hundred, right in the hundreds column.
That leaves 6 hundreds, 2 tens and 5 ones: 625.
A How to Play demo, built in
Tap How to play on the menu and a pointing hand solves 27 + 45 step by step, with a caption for each move: tap ones, loop a row, pick exactly 10, SNAP, then type the answer. Students can watch it on their own, or you can play it on the board to introduce the game.
A builder crew for every right answer
Seven different celebrations take turns, so the cheer still feels fresh on the fifth problem. Finish all five floors and the whole tower is complete.
What students practise
- Two-digit addition with and without regrouping
- Three-digit addition with regrouping into tens and hundreds
- Place value: 10 ones = 1 ten, 10 tens = 1 hundred
- Deciding when regrouping is needed, not just following a rule
- Connecting the model to the written method
Where it fits in your week
- Introducing regrouping. Play the How to Play demo on the board, then solve one together.
- Math centres and stations. One device per student or pair.
- Small groups and intervention for students who are still unsure when to regroup.
- Early finishers. Can they finish the tower on all three levels?
- Review before an addition with regrouping assessment.
Teaching tips
- Say it before you snap. "8 ones and 5 ones make 13 ones. That's a ten and 3 more."
- Write it as you go. Have students record the little 1 above the tens as they make each ten.
- Ask "Do I need to make a ten?" Level 1 mixes in problems that don't need regrouping on purpose. Make students decide before they loop.
- Point to the rows. The two rows are the two numbers. Ask which ten in the top row is the one they just built, and where its 10 ones came from.
- Pair it with subtraction. Making a ten in addition is the reverse of breaking a ten in subtraction: try Subtraction Smash next.
Standards
- 2.NBT.B.5: Fluently add and subtract within 100 using strategies based on place value
- 2.NBT.B.7: Add and subtract within 1000 using concrete models and place value strategies, including composing and decomposing tens and hundreds
- 2.NBT.B.9: Explain why addition and subtraction strategies work, using place value
- 3.NBT.A.2: Fluently add and subtract within 1000 using strategies based on place value
Quick answers
Do students need accounts? No. It's a link, so there's nothing to sign in to.
What devices does it work on? Any device with a web browser, including Chromebooks, tablets and the classroom board.
What grades is it for? Grades 1 to 4. Levels 1 and 2 fit second grade, and Level 3 brings in third grade three-digit addition.
Do students have to use the blocks? No. The blocks are there to help; a right total counts either way.
Get Addition Build
Give students blocks they can snap together, and addition with regrouping stops being a mystery rule.
Get Addition Build on Teachers Pay Teachers
More from Math Curious
- Subtraction Smash: the subtraction partner, where students smash a ten into ones
- 100 Monster Hunt: a hundred chart game for grades 1 to 3
- Chicken Escape: Chapter 1: making 10, place value and regrouping on the farm
- Digital Place Value Tools: build and represent numbers with base-ten blocks
