ever play with a slinky by pushing it down the stairs? well that's not all you can do with slinkys you can learn about waves with them. if two people hold each end of the slinky then move the slinky up and down then you can see a transverse wave that is a mechanical wave to because it have a medium (the metal). You can create all types of frequency's and amplitudes by either moving your hand up and down faster or slower. another wave you can see is a longitudinal wave by pulling the slinky together then letting go. you will see that the wave moves in the same way the velocity does. it doesn't move up and down it moves side to side. so next time you play with a slinky try to create some waves because you will be able to learn something's while having fun!