Explain compression to kids in middle school! HELP!?

Question

Explain compression to kids in middle school! HELP!?

Hi, i need help coming up with fun ways to explain compression and compressive force to middle schoolers!! And just engineering in general as well!!

Answer 1

I'm not sure I understand what you are trying to teach. In the simplest form, compression is pushing and tension is pulling. Where I find it gets interesting is when you show the differences in how things act under tension and compression.

The most obvious case (so simple that it is probably useless here) is pulling versus pushing on a rope. Much more interesting is the case of squeezing a raw egg, end to end, between your palms. No matter how hard you squeeze, you cannot break it. Try it. The reason is that materials cannot fail in pure compression because stuff is being squeezed together. The constantly curving eggshell (technically known as a closed convex shell) transmits loads from one end of the egg to the other through pure compression. No tension or bending force is generated. When you tap the egg on a hard surface (and you will need to do this to show your students that the egg is a real raw egg) the shell breaks because the concentrated point load produces a local bending force in the shell.

Another interesting demonstration might be that of buckling. If you stand a yardstick up on a bathroom scale and start pushing down on it, the scale goes up but at some point the yardstick starts to bow out (technically that is elastic buckiling). At that point, you can continue to push down but the force on the scale will not go any higher, the stick just bends more. This constant force deflection is unique to compression loading. If you have sticks of several lengths (1/4 inch dowel rods from the hardware work fine) you find the shorter the stick the more load it takes to buckile it until, at some point, it just won't buckle. In fact, the theory predict that the buckiling load is inversely proportional to the square of the length.

Again, I am not sure exactly what you are trying to teach so the above may not be what you need. Feel free to e-mail me through Yahoo Answers. I would be happy to offer more help. By way of credentials, I have a Ph.D. in engineering and a fair amount of experiance in teaching.

Answer 2

I was taught compression (with reference to engineering) together with tension.

An example would be a plank of wood fixed at both ends (i.e. a bridge). Whne a force is applied to the bridge (say the center), the 'top' of the plank is in compresion and the bottom of the plank is in tension.

I think it might be well demonstrated with a spring. Push down on the spring for compression, pull the spring for tension...

Maybe then talk about the plank.

Answer 3

how about taking a beaker and putting various things in it and measuring the force applied. try air, a tomato, a piece of watermelon (just the red part), a piece of wood, water. they will learn some things compress but others don't.

springs are also fun to teach with. hook a few pulleys up and you'll have their undivided attention!

Answer 4

Make it fun, in an educational format. Use diagrams to express what they're reading. Displaying things is always a great way to get your point across and have the kids enjoy what's being taught.

Answer 5

try to develop a practical project
let them give the definitions by seeing the effects

Answer 6

tell ythem this:
compression is when i poo and then i have to compress my nasal cavities because it smells soo bad.