The Slap-It Challenge
Can you get a slap bracelet on the arm of a friend (or sibling or parent or another volunteer) from a distance? First 2 feet, then 10 or 12 feet—approaching this as a scientist? We’re inviting kids and families to try your own experiments, and share video of them of course! Post and share them with #SlapIt.
For inspiration, check out this example, or this one.
A few factors to consider as you get started:
- How does throwing technique affect your success rate? Like with horseshoes, darts or skipping rocks, you may need to try different throwing styles and angles to see what works best.
- Obviously, distance increases the challenge. Start close to your target, then see how far away you can move and still get the bracelet on the arm. (We strongly recommend some protective eyewear, by the way.) Record your attempts and success rate at each distance.
- If you have more than one slap bracelet in the house, they may have different coverings, weights or flexibility. Try each one. Are some more likely to succeed than others? Why might this be?
Keep a record of your attempts and the variables, including which were successful, and share your videos with us. Good luck and #SlapIt!
If your child likes learning how things work—in this case, what makes slap bracelets slap—keep reading.
Slap Bracelets and Noggin Builders
At Noggin Builders, we love the humble slap bracelet.
It’s that slightly curved, oversized tongue depressor-like strip that snaps instantly into a coil when you tap or slap it against another object.
We dig slap bracelets so much, we hand out Noggin Builders versions to some of our visitors—like those who come to our Dundee Road location to drop off entries to the Postcard Challenge.
Snap bracelets are elegantly simple and highly addictive—who can resist a good thwack around the wrist? And of course, it’s science in action. Which leads us to…
The science behind the band
A slap bracelet operates the same way as metal measuring tape, which has a slightly U-shaped surface when it’s extended, but flattens when it’s rolled up. And that’s not a coincidence—you can actually make a homemade slap bracelet by covering a segment of measuring tape with a protective and/or decorative covering, like duct tape or rubber.
In the physics world, this is called a bistable spring. “Bi” meaning the band will sit happily when it’s undisturbed in two different states—either stretched out or rolled up. However, in this case, the coiled state is a little more stable than the outstretched one. And that’s why a small tap causes it to snap instantly from outstretched to coiled. When it’s rolled up, you have to pull a bit to stretch it out again.
As you might guess, scientists have found lots of other uses for bistable mechanisms, including switches and latches used in space—even in the wheels of the Mars Exploration Rovers.
If your child is interested in physics and has a few minutes to spare, this video does a nice job of explaining and illustrating bistable springs.
For true slap-bracelet fans, here are a few more fun facts:
- The bracelets were invented by a shop teacher in Wisconsin in 1983 and introduced as “Slap Wraps” in the late ‘80s.
- When the craze returned in the 20-teens, Apple tried to get ahead of the game and filed for a patent on a slap-band for its new watch design in 2013.
