Though it’s short for the nine-thousand-letter polytetrafluoroethylene (count ‘em, 9,000) and therefore sounds super fancy-like, PTFE is actually a pretty common material. It’s most commonly known as Teflon, which is actually a slight variation of standard PTFE (varied just enough to be patented by DuPont). A PTFE coating can make parts in industrial equipment work better and last longer, and PTFE tape is used by plumbers to create a better seal between pipes and pipe fittings. That very same PTFE tape is the key component of this fun and easy Demo Science science demo.
Twisting Your Words
As mentioned, you’ll need a fresh roll of PTFE tape. Also, fine tip permanent markers, and newspaper or scrap paper. Group your smelly little students (or whoever) into pairs and give each duo a marker and a piece of paper. Then, cut a strip of PTFE tape for each kid. (Oh yeah, you’ll also need a scissor.)
Have the little goobers lay their tape strips flat on the scrap paper so their sloppy writing doesn’t spill over onto their desks. Then, give each pair a marker and have them write “secret messages” to their partners. It doesn’t matter what they write, it just has to fit on the tape—so keep the strips small or you’re sure to have one little weisenheimer who writes out the first chapter of The Great Gatsby.
Tell the students not to let their partners see what they’re writing. (Wouldn’t be much of a secret if they did see it.) When they’re done scribbling, the actual fun, interesting part begins.
Have ‘em pick up their tape strips and stretch them from the top and bottom. (Stretch the tape, not the kids.) Pull firmly and steadily, but gently—if the tape rips, the whole thing is ruined. Ruined, I tell ya! Without a heck of a lot of effort, the secret messages should twist and warp and look really weird.
Each student should now try to read their partner’s message. It will be difficult at best, nigh impossible at worst. (Or maybe that’s best. I don’t know. Either way.) How will they ever decode the secret messages?
By pulling the other way! Tell them to stretch the tape a second time, but end to end. The previously warped letters should return to normal (or close to it) and be legible once again. Except for Kevin’s message, because his penmanship is atrocious.
So just how the heck did that work? The molecules in PTFE are arranged in long chains that run side by side and on top of each other. Stretching the PTFE tape end to end right off the bat will do essentially nothing, because of how the molecule chains are structured. But, by pulling it vertically, the stacked chains slide over one another and reduce the number of chains in a section, while never breaking the chain. Pulling the vertically stretched PTFE horizontally slides those chains back into their original alignment.