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STEM Activities Geared towards Middle and High School Students Here are some additional activities, STEM experiments, as well as Apps you can download and explore while you are home from school. Younger students will require parent’s assistance. Table of Contents AIR PRESSURE CAN CRUSHER ................................................................................. 3 BUILD A STRAW BRIDGE ......................................................................................... 5 CODING WITHOUT COMPUTERS ............................................................................ 9 MAKE YOUR OWN ICE CREAM ............................................................................. 10 MAKE YOUR OWN RAINSTICK! ............................................................................. 12 PAPER RECYCLING ................................................................................................ 14 PHONE SPEAKER ACTIVITY ................................................................................... 16 THE UNDERWATER CANDLE EXPERIMENT ........................................................... 17 WATERING SYSTEM FOR PLANTS ......................................................................... 19 NATURE’S WATER FILTER ..................................................................................... 21 SIPHON PUMP...................................................................................................... 23 FOUR FORCES OF FLIGHT EXPERIMENT ................................................................ 25 FREE APPS TO DOWNLOAD .................................................................................. 27 APPS TO PURCHASE ............................................................................................. 29 2 AIR PRESSURE CAN CRUSHER There are many different ways to crush a soda can, but nothing compares to doing the soda can implosion experiment. Materials: Empty soda can Bowl Water Pan for the stovetop (have an adult help with this) WARNING! IMPORTANT SAFETY RULES: This experiment requires the use of a burner on a stove to heat some water. Children should not perform this experiment without adult supervision. Instructions: 1. Start by rinsing out the soda cans to remove any leftover soda. 2. Fill the bowl with cold water (the colder the better). 3. Add 1 generous tablespoon of water to the empty soda can (just enough to cover the bottom of the can). 4. Place the can directly on the burner of the stove while it is in the “OFF” position. (Have an adult turn the burner of the stove on to low. (Soon you’ll hear the bubbling sound of the water boiling and you’ll see the water vapor rising out from the can. Continue heating the can for one more minute.) 5. It’s important to think through this next part before you do it. Here’s what’s going to happen: you’re going to use the tongs to lift the can off the burner, turn it upside down, and plunge the mouth of the can down into the bowl of water. Get a good grip on the can near its bottom with the tongs, and hold the tongs so that your hand is in the palm up position. Using one swift motion, lift the can off the burner, turn it upside down, and plunge it into the cold water. Don’t hesitate . just do it! How did this work? What force is great enough to crush the can? 3 How does this work: Before heating, the can is filled with water and air. By boiling the water, the water changes states from a liquid to a gas. This gas is called water vapor. The water vapor pushes the air that was originally inside the can out into the atmosphere. When the can is turned upside down and placed in the water, the mouth of the can forms an airtight seal against the surface of the water in the bowl. In just a split second, all of the water vapor that pushed the air out of the can and filled up the inside of the can turns into only a drop or two of liquid, which takes up much less space. This small amount of condensed water cannot exert much pressure on the inside walls of the can and none of the outside air can get back into the can. The result is the pressure of the air pushing from the outside of the can is great enough to crush it. The sudden collapsing of an object toward its center is called an implosion. Nature wants things to be in a state of equilibrium or balance. To make the internal pressure of the can balance with the external pressure on the can, the can implodes. Air pressure is powerful! You probably noticed that the can was filled with water after it imploded. This is a great illustration of how air is pushing all around us. Specifically, the outside air pressure was pushing downward on the surface of the water. Since the air pressure inside the can was less than the pressure outside the can, water from the bowl was pushed up and into the can. This action is similar to what happens when you drink from a straw. Though we say we are “sucking” liquid up through the straw, we really aren’t. To put it simply, science doesn’t suck . it just pushes and pulls. Outside air pressure is pushing down on the surface of the liquid. When you reduce the pressure in your mouth (that sucking action) the outside pressure is greater than the pressure inside your mouth and the soda shoots up through the straw and into your mouth. The same thing is true with the can. The outside air pressure pushing downward on the surface of the water is greater than the force inside the can and the water gets pushed up into the can. Reference: https://www.stevespanglerscience.com/lab/experiments/incredible-can-crusher/ 4 BUILD A STRAW BRIDGE Materials: 2 tables or chairs Tape measure 200 pennies or metal washers 1 roll of tape Scissors Small paper cup 20 straight (not flexible) drinking straws The goal is to design a bridge that can span a gap of at least 10 in by using only tape and no more than 20 straws. Your bridge will need to support as many pennies as possible. Getting Ready: Set up the tables or chairs 10 in apart from each other. This is long enough that a single straw (about 8.5 in) will not span the gap. (If you are using longer straws, enlarge the gap to maintain the challenge.) Introduction: Bridges are a crucial part of our infrastructure. Not only do they help us get to our destinations, they allow us to cheaply and efficiently transport goods across long distances and many obstacles. Life would be very different without bridges. Bridges and those that cross them are acted upon by several forces. Gravity is always working to pull a bridge down. The load on a bridge causes additional stress on the materials, resulting in parts of the bridge being squeezed together (compression) while others are pulled apart (tension). Suspension bridges are also susceptible to twisting (torsion) forces caused by wind. Bridges come in a variety of designs, including suspension, cable-stayed, beam, arch, and truss. Truss bridges use a series of triangles for support and are commonly used for railroad bridges because of their incredible strength. You can demonstrate the strength provided by triangles by making a square out of tape and straws. Manipulating the square easily deforms the shape. But add a diagonal straw (or two) across the square and feel the difference. 5 Instructions: 1. Work on building your truss bridge that spans at least 10in using only your 20 straws and tape. 2. Once your bridge is complete, place a paper cup on the center of the bridge’s span and begin placing your pennies or metal washers in the cup one at a time to measure how much weight it can support. Observe how the bridge deforms (or collapses) under stress. Keep count of how many pennies or washers the bridge was able to support. Use a tape measure to measure how low the bridge hangs under stress. Redesign and retest bridges as necessary. Troubleshooting: If a bridge does not naturally hold a paper cup, create a deck with some thin, light cardboard or material from a cereal box. Terminology: Compression: A force that squeezes an object from opposite directions, pushing two points towards each other. Smashing a can with your foot puts it under compression. Span: To extend from one side of something to the other side, as a bridge does over a river. Tension: A force produced from stretching or pulling something in opposite directions. A tug-of- war rope is under tension. Truss: A structure made out of triangle shapes and designed to carry heavy loads. GUIDANCE FOR YOUNGER CHILDREN QUESTIONS TO ASK AFTER THE ACTIVITY How many pennies or how much weight was your bridge able to withstand before breaking? Was this more or less than you expected? What are two things that you, as well as engineers, consider when designing bridges? If you had more time to make another bridge or change your design, would you do anything differently? Why? Can you think of any other structures that use trusses or triangles for support? What was the most challenging part of this activity? 6 ENGINEERING CONNECTIONS A bridge is a structure that allows people or vehicles to cross over an obstacle such as a gorge, valley, road, railroad track, or body of water, rather than going around it or through it. There are many different types of bridges, including suspension bridges, cable-stayed bridges, arch bridges, and truss bridges. In determining what type of bridge to build, engineers must consider how heavy a load the bridge must support and how far it must span. The load is the weight and all of the forces that a bridge must be able to support. There are two types of loads that engineers consider when designing bridges: the dead load and the live load. The dead load is the weight of the bridge itself. Bridges are usually built from concrete and steel and are, therefore, very heavy. They have to hold themselves up before they can hold all of the people and vehicles that will use them! The live load is the weight of all of the other things— people, cars, bicycles, snow, and wind—that will also be added to the bridge. Bridges have A LOT of weight to hold up! SCIENCE CONNECTIONS For a bridge to remain standing, it must be able to apply a force that is equal to everything on it, but that acts in the opposite direction.

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