You might not even notice it, but every minute you’re awake, you have to blink your eyelids. Your body does this without you even trying, and for a few reasons. Blinking keeps our eyes wet, pushes dust out of the way, and gives our brains quick, restful breaks from looking at stuff. So our friend Alexis V. asked, how many times do we blink while watching a movie? (And happy birthday Alexis!) To figure that out, we need to know how many times we blink in 1 minute, and that depends on what we’re doing. We normally blink 15-20 times per minute, which means our eyes are closed about 1/10th of our whole time awake. BUT scientists have found that we blink less often when we’re watching something interesting — like a movie. That said, even if we drop to 10 blinks a minute, over a 2-hour movie our minds will still get lots of breaks, as we’ll find out when we do the math.

*Wee ones:* If you blink 8 times, what numbers do you say to count those blinks?

*Little kids:* Kids blink less often than grownups — you blink faster and faster until you’re 14! How many years from now is that for you, or how long ago was it? *Bonus:* Babies blink only 2 times a minute. How many minutes does it take for them to blink 6 times?

*Big kids:* If a movie lasts 2 hours, how many minutes of blinking is that? *Bonus:* If you then blink 10 times every minute, how many times do you miss out on little bits of the movie?

*The sky’s the limit:* If a kid blinks only 2/3 as often as a grown-up, and blinks 20 times less during a Youtube video, how many times does each person blink?

Answers:

*Wee ones:* 1, 2, 3, 4, 5, 6, 7, 8.

*Little kids:* Different for everyone…count up to find the years until you’re 14, or count down from your age to 14. *Bonus:* 3 minutes.

*Big kids:* 120 minutes. *Bonus:* 1,200 times.

*The sky’s the limit:* 60 times and 40 times. If the kid blinks only 2/3 as much, then the difference in their blink counts will be 1/3 of the grownup’s total. We know that difference is 20, so the grownup must blink 60 times, and from there the kid will blink 40 times.

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.