AZ 4-H STEM at Home
Phone Book Friction
A popular science demonstration shows that when you overlap the pages of two phone books, they are nearly impossible to pull apart. If you do not have two phone books sitting around, you can do the same experiment with sticky notes. Sticky notes are much smaller than phone books, so they should be easy to pull apart, right?
Try this activity to find out!
Learn about Liquid Density
Different liquids have different densities based on their weight. A cup of oil, for example, will weigh a little less than a cup of syrup. Liquids with the highest density will sink to the bottom, while liquids with a lower density will rise to the top. Pour different liquids into a single jar and wait for them to separate. It shouldn’t take more than a minute or so. In general, density is how many particles are inside each liquid. In an equation, density equals mass divided by volume. When the mass of an object increases but the volume stays the same, the density increases.
See if your guesses were right, or if you were wrong.
Water Cycle in a Bag
Earth’s water is constantly moving and being recycled. Warm liquid water, heated by the sun, evaporates into water vapor. When water vapor cools it condenses, changing back into liquid or solid if it’s cold enough, falling as precipitation in the form of rain, sleet or snow. In the real water cycle, precipitation might land in a body of water like a river or ocean. But it also might fall on land where it soaks into the soil and either becomes ground water that people rely on or it runs over the soil and into rivers, lakes or oceans.
Make your own water cycle in a bag to watch it in action!
Drop raisins into a glass of water. What happens? Drop some into some carbonated liquid and see what happens. What makes the raisins appear to ‘dance’ around?
Can you figure it out? Share with your friends!
Make Plastic Ornaments from Milk
Milk contains many molecules of a protein called casein. Each casein molecule on its own is a monomer but a chain of casein monomers is a polymer which can be molded. Plastic made from milk is called casein plastic. From the early 1900s until about 1945, milk was commonly used to make many different plastic items, including buttons, decorative buckles, beads and other jewelry, fountain pens, the backings for hand-held mirrors, and fancy comb and brush sets. Milk plastic was even used to make jewelry for Queen Mary of England!
You can make your own milk plastic out of hot milk and vinegar!
Air in a ketchup packet allows it to float in water. But when you squeeze a sealed bottle of water with the packet inside, you compress that air into a smaller space. This increases its density, and the overall density of the ketchup packet. When the packet becomes denser than the water, it sinks (Density = Mass divided by Volume). When you release the pressure on the bottle, the compressed air expands again inside the packet (increasing the volume), the density decreases, and the diving ketchup floats back to the top of the bottle.
Try this out and share the science trick with your friends!