Silly putty bounces like a rubber ball (except higher), will break from a sharp blow, can be stretched, and will melt into a puddle after a length of time. If you flatten it and press it over comic book or some newpaper print, it will copy the image.
Bouncing Silly Putty
If you shape Silly Putty into a ball and bounce it off a hard, smooth surface it will bounce higher than a rubber ball. Cooling the putty improves its bounce. Try putting the putty in the freezer for an hour. How does it compare with warm putty? Silly Putty can have a rebound of 80%, meaning it can bounce back to 80% of the height from which it was dropped.
Floating Silly Putty
The specific gravity of Silly Putty is 1.14. This means it is more dense than water and would be expected to sink. However, you can cause Silly Putty to float. Silly Putty in its plastic egg will float. Silly putty shaped like a boat will float on the surface of water. If you roll Silly Putty into tiny spheres, you can float them by dropping them into a glass of water into which you have added a little vinegar and baking soda. The reaction produces bubbles of carbon dioxide gas, which will stick to the spheres of putty and cause them to float. As the gas bubbles fall off, the putty will sink.
The Solid Liquid
You can mold Silly Putty into a solid form. If you chill the putty, it will hold its shape longer. However, Silly Putty isn't really a solid. Gravity will take its toll, so any masterpiece you sculpt with Silly Putty will slowly soften and run. Try sticking a glob of Silly Putty to the side of your refrigerator. It will stay as a glob, showing your fingerprints. Eventually it will start to ooze down the side of the refrigerator. There is a limit to this -- it won't run like a drop of water. However, Silly Putty flows.