This game builds number sense and a playful approach to math.
Many parents remember struggling to learn math. We hope to provide a better experience for our children. And one of the best ways for children to enjoy learning is through hands-on play.
So what are you waiting for? Let’s play some math!
Next-Door Neighbors
Math Concepts: number properties, numbers within 100.
Players: two players, child and adult.
Equipment: printed hundred chart.
Set-Up
The free 50-page PDF Hundred Charts Galore! file offers many variations of hundred charts. Choose your favorite, or change it up each time you play.
How to Play
Ask your child to choose any two next-door neighbor numbers — that is, two numbers in side-by-side squares — but not to tell you which ones. Then the child should add the numbers and tell you the sum.
Can you show off your magical skills by identifying the original numbers? Just subtract one from the sum, and then divide that new number in half to find the smaller of your child’s two neighbor numbers.
It may take several tries for children to figure out this trick. After they get it, take turns adding neighbor numbers for the other person to guess.
Variations
Do you notice a pattern in the next-door neighbor sums? Will the total always be odd? Why, or why not?
What will happen if you add two apartment-house neighbors (one number above the other) — will the answer still be odd? Can you think of a “magic trick” pattern to identify the original numbers from their sum?
What about two numbers that sit diagonal to each other, touching at a corner?
Answers to the Puzzle
Teacher’s Tip: Don’t peek. Nobody likes a spoiler……………Next-door neighbor sums are the same as the double of the smaller number, plus one. To find the original numbers, subtract that extra one and then divide the answer in half. That will give you the smaller of the two numbers.
The next-door neighbor sums are always odd because they are doubles-plus-one, which is the definition of an odd number.
Apartment-house neighbors are ten apart, numbers like 32 and 42. If someone tells you the sum, you can subtract that extra ten and then divide the result in half. That will give you the smaller of the two numbers — then add ten to get the larger number.
But numbers that sit diagonal to each other may be either nine or eleven apart. Since you don’t know which way the diagonal slants, there is no way to discover them just from their sum.
This game is an excerpt from 70+ Things To Do with a Hundred Chart, available at my bookstore (Thank you for cutting out the middleman!) and through many online retailers. Read more about my playful math books at my publisher’s Tabletop Academy Press website.
Special Offer: Would you like to access a growing archive of Math Monday games and other activity ideas as convenient printable pdf downloads, ready to print and play with your kids? Join me on Patreon for mathy inspiration, tips, printable activities, and more.
“Math Game Monday: Next-Door Neighbors” copyright © 2024 by Denise Gaskins.
