River Race
River Race is one of our free addition and subtraction games for ages 6 to 8. Solve a two-digit sum to paddle your boat forward, one turn at a time.
You
🛶🏁
Mathumo
⛵🏁
How to play
Solve a two-digit sum to paddle your boat forward, one turn at a time.
- These addition and subtraction games have three modes: Add, Add with regrouping or Take away. Pick one.
- You and Mathumo each have a boat on a river with 12 steps.
- Each turn there is a two-digit sum, for example 34 + 25. Tap the answer.
- Right the first time: your boat paddles 2 steps. Right after a try again: 1 step. Mathumo paddles 1 step every turn.
- If it is not the right answer, read the hint (tens first, then ones) and try another piece.
- The first boat to reach the flag wins. Race as many times as you like.
After a second try, the hint shows the whole working with tens and ones, so you can see how the answer is built.
What children learn
- Tens and ones: splitting 34 into 30 and 4 and adding the tens and the ones separately.
- Regrouping: carrying when the ones make ten or more, and borrowing when taking away.
- Two-digit addition and subtraction: within 100, with the working shown after a miss.
Guides for parents
Ideas for playing and talking about math away from the screen, related to River Race.
How to teach subtraction so it makes sense to your child
Teach subtraction in a sensible order: taking away, counting back on a number line, finding the difference and thinking addition. With common mix-ups.
Math board games for kids: what to play at ages 3 to 8
Math board games for kids, by age: race tracks, dominoes, sowing games, Shut the Box and dice games, plus how to make your own number track at home.
Place value: teaching tens and ones with things at home
Place value means a digit's position gives its worth. See how to teach tens and ones with bundles, why 14 is ten and four, and the mix-ups to expect.
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Questions about River Race
What are good addition and subtraction games for ages 6 to 8?
Good addition and subtraction games for this age work with tens and ones and show the working after a miss. In River Race each turn is a two-digit sum, and the hint takes the tens first, then the ones. Children should already be comfortable adding and subtracting within 20, and there is no timer.
How do you add two-digit numbers?
Add the tens, then add the ones, then put them together. For 34 + 25, the tens are 30 + 20 = 50 and the ones are 4 + 5 = 9, so the answer is 59. Children can check it by counting on from the bigger number in tens, or by drawing it as tens rods and ones blocks.
What is regrouping in addition?
Regrouping, also called carrying, happens when the ones add up to 10 or more. For 47 + 25, the ones make 7 + 5 = 12. That is one ten and 2 ones, so the 10 joins the tens: 40 + 20 + 10 = 70, and 70 + 2 = 72.
How do you subtract two-digit numbers?
Take away the tens first, then the ones. For 57 − 24: 57 − 20 = 37, then 37 − 4 = 33. When there are not enough ones, such as 62 − 27, take the ones in two steps: 62 − 20 = 42, then 42 − 2 = 40, then 40 − 5 = 35.
What is borrowing in subtraction?
Borrowing, also called regrouping or decomposing a ten, is used when the ones digit of the starting number is smaller than the ones digit being taken away. One ten is broken into 10 ones so there are enough to take from.