Math with dominoes

October 11, 2015

Dominoes make excellent math manipulatives, and we have begun to use them frequently in our homeschooling. There are lots of different games that can be played with them and in the process of playing the games a preschool child can start to recognize patterns like that nine is three groups of three or that two odd numbers added together make an even number.
When I play dominoes with my four year old we talk about the dots as though they could move. We have four and two. What if one of the dots on this side moved over to that side? What would we have then?

Here are the rules to a few of the games we’ve been playing recently.

Lonely Domino
Start with all the dominoes face up. Choose one domino and announce that is lonely and wants to join up with one or more dominoes whose number of dots total up to eight. Once the child has found an appropriate domino or pile of dominoes, place them next to the first domino and announce that the new domino (or pile of dominoes) is lonely and wants to find one or more friends with dots totaling up to twelve. Keep naming off different numbers, occasionally repeating numbers so that the child can see that there are more than one way to create the appropriate number. Keep an eye on which dominos are left and which numbers can be formed.

Domino War
Play just like the card game war, but flipping dominoes instead of cards. Encourage the child to guess who has the higher number before naming the number. You can both flip one domino, or you can flip two at a time adding them together before comparing the total with the other player’s. You can also incorporate subtraction into the game. Flip a single domino and subtract the smaller side from the larger side before comparing the difference with your opponent’s.

Which is missing?
Take two dominoes. Announce the total number of dots and then show the child one of the dominoes. Ask how many dots must be on the other domino. Then let the child have a turn taking two, totaling them and asking you which number must be on the missing dominos. If you can keep it casual enough you can challenge the child to figure out what possible combinations of dots there are that would make up the missing number.

Domino collections
Lay all the dominos out face down. Take turns removing dominos and recording the number of dots. With an older child just use a sheet of paper and count up the dots. With a younger child use an abacus or write the number of dots with tallies – four lines with the fifth going across, and two sets of five per row. Practicing with tallies or an abacus helps the child to recognize ten, twenty, thirty, etc as being groups of tens, and it helps give practice at recognizing patterns like if you have seven (five and two) already out, you need three more to finish up the row of ten.

I’m thinking of a domino that….
Lay all (or a handful) of dominoes face up. Choose which one will be your secret domino but don’t announce it out loud. Give clues such as “one side of the domino has twice the number of dots as the other does” or “the domino has a total number of dots less than 8″ or “one side of the domino has an odd number of dots, the other has an even number.” For each clue, encourage the child to remove all the dominoes that do not meet the criteria.
Then switch players and let the child think up enough clues for you to figure out his or her secret number. The challenge of thinking up clues is a great one.

What’s my rule?
Another way to reverse the previous game is to think up a rule and without announcing what the rule and start sorting the dominoes according to that rule. You can allow the child to join in with their guesses or just ask him or her to wait until you’re finished. Then ask the child what they think the rule is? What does your group of dominoes have in common that the others do not have?