Most people are right-handed, which means they use their right hand to write and generally feel stronger using their right side. However, there are people out there who are left-handed, which means that they write with their left hand, and probably pour drinks, brush their hair, and do lots of other things lefty. In the old days, everyone thought left-handed people were a threat to society. But don’t worry, now that we have Google to look up all this stuff, we know that being lefty isn’t bad at all. In fact, it might mean you’re better at certain things, like music and math. You will, however, have to get a different-shaped glove to play catch.
Wee ones (counting on fingers): How many people in your family are left-handed…and so then how many are right-handed?
Little kids: If your class has 23 kids and 4 of them are left-handed, how many right-handed kids are in your class? Bonus: If half of those 4 left-handed kids can also write just as well with their right hands (meaning they are “ambidextrous”), how many right hands in the class can write?
Big kids: About 1 out of every 10 people in the world is left-handed, but of the last 20 presidents, 7 have been left-handed! (and from both parties, interestingly…) How many more left-handed presidents is that than if only 1 out of every 10 had been left-handed? Bonus: There was just 1 left-handed president before these 20, which means that only 8 out of our 45 presidents have been left-handed. So how many were right-handed?
Wee ones: Different for everyone…count the number of lefties, and then subtract from the total number of people in your family.
Little kids: 19 people. Bonus: 21 right hands: the 19 righties, plus the 2 both-handed.
Big kids: 5 more presidents, as probability says there should have been only 2! Bonus: 37 right-handers.
Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.