# Motion Math Blog

### 3 Subtraction Activities For Family Fun Night

Many young children experience difficulties in learning subtraction. These difficulties arise early and continue into second grade and beyond, largely because many students fail to move beyond inefficient counting strategies for answering unknown subtraction facts.Carol A. Thorton and Paula J. Smith

When your child is learning, and perhaps struggling with, subtraction, one way you can help is exploring the concept of subtraction as both “difference” and “take away”. Difference is comparing two sets of similar items (i.e. buttons, cookies or M&M’s). Take away is removing items from a larger set. For example, for seven minus five:
Is this difference or take away? Your child has picked seven flowers for you. You look next door and see that your neighbor has five flowers. You ask your child, “how many flowers does Mommy or Daddy have, compared to how many flowers our neighbor has?”
Is this difference or take away? Using cheerios as counters, put out seven cheerios. Let your child eat five before you ask, “how many cheerios are left?”

These three fun math activities let you strengthen your child’s relationship with subtraction while you also bond as a family!

How Close Can You Get?
You need a deck of cards, with the tens, Jacks, Queens and Kings removed. You also need a piece of paper and pencil. Please note that Ace = 1 for this game.

1. Each player gets four cards, placed face down.
2. Turn up two cards from the deck. The first card, say a six, gets the tens’ place. The second card, say an ace, gets the ones’ place. These two cards are the target number, in this case, a 61.
3. Each player reveals his or her four cards and rearranges them into two 2-digit numbers so that when they are subtracted, they are as close to the target number as possible.
4. To score, each player finds how close he or she got to the target number. For example, I have an ace, 5, 3 and 9. So the best I can do is a 95- 31 = 64, with 64 – 61 = 3 (score). Please note you can go over or under the target number when you subtract. A 57 would give me 61 – 57 = 4 score.
5. Repeat steps 1-4 for the next round.
6. Play for five rounds. The player with the lowest total score wins.

Variations of this math game:
• Try a 3 digit target number and six cards for each player.
• Playing with younger kids? Try a 1 digit target number and two cards for each player.

For discussion:
• What did you find the most interesting about How Close Can You Get? and why?
• Did you like playing with two or three digit numbers the more? How come?
• How did you keep the different possible combinations straight?
• Can you think of other situations that you’ll need to know subtraction? What are they?

This fast moving game is great for family fun night. Each player needs a sheet of paper, pencil and die.

1. Each player should write “99” at the top of his or her sheet of paper to start.
2. For each round, players should roll their die and then subtract the result on their sheet of paper. So if I rolled at 2 and a 3, I would write “99 – 5 = 94”.
3. Repeat #2 until one player gets to zero.
4. If players make a mistake in their subtraction, have them explain their reasoning. If they are struggling with regrouping (also known as “borrowing” or “carrying over”) check out this blog post, How to Help Your Child Learn Subtraction.

Variations of this math game:
Use pairs of different color die One color represents the tens place, the other the ones place. So rolling a 2 and a 3 (per above) would be either a 32 or a 23, depending on the die color.
For longer rounds, start with larger numbers, such as 999 or 1919.
For speed rounds, set a kitchen timer for 90 seconds – play Countdown! until time runs out. The winner is the player that gets closest to 0 without making a mistake in his or her subtraction. If mistakes are made, it’s ok (it’s just a game!) but figure out why, as a family.
For younger players, start at a smaller number (49) and only use one die.

For discussion:
• What was your favorite round and why? (Winning, while great, should not be the only answer!)
• What did you find most challenging about Countdown! and why? Are certain numbers easier to subtract?
• If you could make the rules for the game, what rule would you include or get rid of? Why? How do you think it would change the game?

Motion Math: Hungry Fish, our mental arithmetic game for ages 4 to 44

You will need iOS device, such as an iPad, iPhone or iPod Touch.

1. Download Motion Math: Hungry Fish from the App Store. You can buy the subtraction levels from within the app.
2. Play through the intro level, joining two bubbles together to form a sum with instant addition. Then, feed the sum to your hungry fish.
3. Explore the different subtraction levels in both the reef and the cave. What happens when you make an incorrect difference in the cave?
4. Win additional colors and fins to customize your fish – you can even name it!

Tap the fish icon to create a new player. That way, different kids can compare the colors and fins they’ve won. They can also discuss the different levels of the reef and cave they’ve swum through.

For discussion:
• What are the many ways can you make a difference with two bubbles? For example, what combinations would you feed a fish that eats “9”?
• Can you draw a picture of all of the bubbles you’d want for your fish, if your fish has a 7 on it?
• Did you like the reef or the cave better and why?

We hope you enjoy these subtraction activities with your family. Some, such as Countdown! are perfect for the playroom rug. Other games, such as Motion Math: Hungry Fish, can be played anywhere.

Which these games your family has played and what did you think? If you have other subtraction activities or games you like, please share them in the comments!

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### 3 Responses to “3 Subtraction Activities For Family Fun Night”

1. Interesting subtraction games! My boys are loving Hungry Fish app. We just wish that there were more colors available. There seem to be only 3 colors, no matter how many levels we accomplish!
One of their favorite parts of the app is to be able to eat the bad fish in the caves once they are big enough!

2. Cate, I’m glad your boys are enjoying Hungry Fish and it sounds like they’re having a lot of the fun with the cave levels. 🙂

I promise you and your boys have more than three colors – just keep playing for the colored pearls. Have you unlocked the different fins yet?

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