HOW DOES IT WORK:

The most commonly accepted explanation for this experiment is a phenomenon called laminar flow.  Laminar flow happens when a fluid moves in thin sheets or layers that glide alongside each other, but never actually mix together.  As the inner container is rotated, the sticky (or viscous) fluid will begin to twist after it, one layer at a time.  As the layers of dyed syrup remain separate within their original layers of syrup, the dots will appear to stretch and blend together; however, the layers of color are simply overlapping, giving the appearance of blending together!  From the side, the overlapping layers of colors give the appearance of mixing together.  But if you look downward into the gap between the two containers, you will actually see how the thin layers have rotated, but not actually mixed together!

When you rotate the inner glass in the other direction, the layers of fluid simply twist back until the layers of colored syrup all line up in their original formation.

THE MORE YOU KNOW:

When you turn on the kitchen faucet at home, you might notice a lot of ripples or bumps in the stream of water—maybe some water droplets even jump out of the stream!  This is because the water is very likely moving in a turbulent flow.  Turbulent flow is characterized by an uneven flow of liquid, causing small swirls and ripples within the stream.

There are special faucet attachments that can create a more stable Laminar Flow stream of water. These faucets produce very clear and glass-like water streams that are often used in decorative fountains and even in amusement park water displays!

GOING ONE STEP FURTHER:

1. Repeat the experiment using a different viscous substance.  You could try using vegetable glycerin, coconut oil, or even a clear liquid hand soap.  Which substance creates the best “un-mixing” result?  Do the less-sticky substances work better, or the more-sticky substances?
2. Repeat the experiment using MULTIPLE viscous substances.  For example: You might fill the outer container 1/3 full of vegetable glycerin, but insert drops of colored liquid hand soap!  If the dyed droplets have a different viscosity than the substance around them, will the colors ever fully “un-mix”?
3. You can completely change the experiment to test a Turbulent Flow.  Instead of using an inner container to twist the fluid, simply mix the dots of dyed syrup with a kitchen spoon.  Once the colors are thoroughly mixed, can you “un-mix” them?  Why or why not?

Happy New Year, science friends! Just go with the (laminar) flow!

INSTRUCTIONS:

1. With help from your adult assistant, cut in half the wire of a double-ended Alligator Clip Lead. Strip away about ½ inch of the plastic coating from each of the cut ends.
2. Using the electrical tape, attach the exposed copper wire directly to each of the Positive and Negative terminals of the AA battery. Use plenty of electrical tape here, because the tape will help to insulate the wires from possibly shocking anything, and it will keep the wires from getting shaken off from the battery.
3. Using a hot glue gun, attach the AA battery to the top of your Scribble-Bot (which is actually the bottom of your recycled container). Allow the glue to thoroughly cool down before handling the Bot.
4. Cut an unused glue stick in half. Attach a piece of the glue stick onto the metal arm of the DC Hobby Motor by pushing the metal directly into the un-melted glue stick. The motor should not be attached in the exact middle of the glue stick, but about ¼ of the way down.
5. Carefully glue the DC motor onto the top of your Scribble-Bot (be careful to not cover any copper tabs that may be on your motor! We will need to attach wires to them later!). You could either place the motor upright on the top of the Bot OR you could glue the motor sideways, making sure the glue stick arm hangs far enough over the side of the top of the Bot to freely spin. Allow the glue to thoroughly cool down before handling the Bot.
6. Using Duct tape, secure 3-4 Washable markers around the sides of your Scribble-Bot. The (capped) marker tips should face downward, and all makers should be evenly spaced and leveled.
7. Now get creative! Decorate your Bot using Googly Eyes, paint, glitter, construction paper, or anything else to make your Scribble-Bot look awesome!
8. Once your Bot is fully decorated, it’s time to test it out. Place a large sheet of white paper on a clear, flat surface. Remove the marker caps from the Bot’s legs and set them aside.
9. Carefully attach one of the Alligator Clips to one of the tabs coming from the DC Hobby Motor. Do you notice any movement? Why or why not?
10. Carefully attach the other Alligator Clip to the other motor tab. Why do both wires need to be attached before the Bot turns on?
11. Set the Bot on the center of the white paper and watch as it creates a unique piece of Modern Art before your eyes! (You might need to guide the Bot back onto the paper from time to time, as the Bot will likely wander off…but that’s why it’s important to use WASHABLE markers!)
12. When finished, unplug both Alligator clips from the motor and secure all marker caps. Wash up any stray markings made around your paper. Most importantly, be sure to hang your Scribble-Bot’s masterpiece in a prominent location!

HOW DOES IT WORK:

Electric Motors are used in many different electronics today. They can be found in electric cars, planes, trains, elevators, kitchen blenders, ceiling fans, computer disk drives, electric toothbrushes, vacuum cleaners, washing machines, electric toys, and even in your cell phone to make it vibrate when a friend calls! In each of these cases, the motors use electrical energy to create mechanical energy that can be used to rotate, vibrate, or drive an object. The arm of the motor (called the Drive Shaft) spins around when the motor is connected to the battery by a closed circuit of wires. A circuit is a closed conductive path that allows electricity to flow from a power source (like our AA battery) to run an electric appliance. If any one of the wires comes undone or is unplugged, the circuit can no longer allow electricity to flow and the motor will not run.

Because we attached an unbalanced weight to the Drive Shaft, the spinning weight will cause the Scribble Bot to continuously tilt from one side to another, causing the Bot to jitter around and seem to move on its own. This motion is especially visible when we attach markers to the Bot.

INSTRUCTIONS:

1. (Optional) Inflate the balloon but do not tie it closed. While pinching the balloon shut, you can draw a design, a picture, or even a face (like a Jack-o-Lantern face!) on the inflated balloon using a permanent marker. Let the balloon deflate and allow the marker ink to dry for about 90 seconds.
2. Insert the neck of a funnel into the opening of the balloon.
3. Ask an adult assistant to break apart some dry ice into small, pea-sized pieces using a hammer or mallet (and remember to wear your protective goggles and gloves!).
4. Using a pair of salad tongs or a spoon, place 10-15 small pieces of dry ice into the funnel, and push down the dry ice into the balloon.
5. Tie off the balloon (without inflating it!).
6. Hold and shake the balloon in your hands for a few seconds, then pass it to a friend to hold for a few seconds. You can play a very chilling game of “Cold Potato” as the Dry Ice inside of the balloon starts to warm up and seemingly disappear.
7. Continue to shake and pass the balloon around until you cannot hear any pieces of dry ice moving inside of the balloon. What has happened to the Dry Ice inside the balloon? Have you observed any changes to the balloon itself? How might this change have happened to a sealed balloon?

INSTRUCTIONS:

1. Fill a small fish tank to about 4 inches of room-temperature water.
2. Ask an adult assistant to add 2-3 large pieces of Dry Ice to the tank of water (using insulated gloves and goggles!), and allow the Dry Ice to bubble for 10 minutes.
3. Using the bubble wand, blow a number of bubbles into and around the Dry Ice tank. Do you notice a difference in how the bubbles act when they float into the tank? What might cause them to act this way?

1. Light one or more candles and set them in a row on a clear, flat surface.
2. Using the beverage pitcher or a measuring cup, scoop up some air from around the room. Reach up high and down low to fill the container with air! Slowly pour the air over the candles, watching for any change in the candles.
3. Again using the beverage pitcher or measuring cup, scoop up some air from inside of the Dry Ice tank. Scoop air as far down as possible, without actually scooping any of the water at the bottom. Again, pour this air over the candles. Do you notice a change this time? Why might the air inside of the tank be different from the rest of the air in the room, and why might it affect the candle flames?

1. Fill a large plastic bowl (or other wide-mouth container) ¾ full of warm water. Ask an adult assistant to add 1-2 large pieces of Dry Ice to the bowl (using insulated gloves and goggles!). Now wouldn’t THAT look awesome as a Halloween decoration?!?!
2. Thoroughly soak a shoelace or a thin piece of fabric in a bowl full of bubble solution.
3. Using your finger, coat the rim of the plastic bowl with a layer of bubble solution.
4. Hold the bubble-soaked straight taught and run it across the surface of the bowl. Make sure the string touches both sides of the bowl as you drag the string from one end of the bowl to the other. You should see a bubble film forming on the bowl’s surface. Be patient if the bubble film doesn’t form on your first attempt! Keep trying until you get it just right!
5. Once the bubble surface has formed, sit back and watch as a mega-bubble grows from the container! Be extra observant of the moment the bubble eventually pops! What happens to the cloudy air inside of the bubble? Does it rise upward or does it fall downward?

Build a Electric Motor (Dancing Wire)

MATERIALS:

• AA Battery
• Neodymium Button Magnet (Can be purchased online or at a few hardware stores)
• Bare Copper Wire
• Safety Gloves
• Wire cutter
• Pliers (only needed if your copper wire is too thick to bend by hand)
• Adult Assistant

INSTRUCTIONS:

1. Carefully place the neodymium magnet on the negative terminal (the flat side) of the AA battery. Neodymium magnets are extremely strong rare-earth magnets, and they could possibly pinch your finger tip between the battery and the magnet, so be VERY careful!
2. Cut a piece of copper wire about 1 foot long (this does not have to be exact).
3. *It is strongly recommended that you wear safety gloves when bending the wire! Once cut, the wire ends are usually very sharp!* Either by hand or using a pair of pliers, bend the wire to form a balanced motor apparatus. The photo to the right demonstrates one way to shape the wire into a symmetrical frame, but any shape that can balance from the positive terminal of the battery will work. The wire must also hang down so that it also makes contact with the battery.
4. Place the neodymium magnet/battery apparatus on a flat surface. Carefully balance the copper wire on the positive end of the battery (it may be helpful to press an indentation into the terminal’s dimple, simply by pushing a pen tip into it.
5. If you don’t see motion right away, then give the copper wire a gently tap to get it going. If the wire still is not moving, you may need to reshape the copper wire for a better connection. Remember, the wire must be able to balance on the positive terminal of the battery while also making contact with the battery below.

HOW DOES IT WORK:

A Homopolar Motor is an example of a very simple Electric Motor. Electric motors are machines that can use electrical energy to create mechanical energy (in other words, they create motion from electricity.) The rotational motion of a homopolar motor is caused by something called the Lorentz Force. This force cannot be directly seen, but its influence is very noticeable. The Lorentz Force has been described by the following:

“A conductor with a current flowing through it, when placed in a magnetic field which is perpendicular to the current, feels a force in the direction perpendicular to both the magnetic field and the current.”

Wow. That’s a pretty intense description, but it is saying that an electric current that is flowing through a wire at a right angle to a magnetic field force will actually be pushed in a direction that is at right angles to both the current and magnetic field. Are you as confused as I am?

The ‘Right-Hand-Rule’ of electricity and magnetism is a trick that might help us more easily explain how the Lorentz Force works. Use the diagram below to visualize the direction of the electrical current (blue arrows), and the magnetic field (red arrows), particularly at the section within the pink circle.

With your right hand, point your index finger in the direction of the flow of electric current (to the left). At the same time, point your right-hand middle finger in the direction of the magnetic field (down). Finally, stretch out your right-hand thumb as far as it can go. Your thumb (which should be pointing directly toward yourself) is now pointing in the direction of the Lorentz Force. Knowing this, we would expect the wire to spin counter-clockwise around the battery!

GOING ONE STEP FURTHER:

1. If the neodymium magnet was flipped upside down, you would also flip the directions of the magnetic field forces. Would the copper wire spin in the same direction, or in the reverse direction, if you flipped the magnet? Use the Right Hand Rule to help develop a hypothesis.
2. Instead of using the Lorentz Force to spin a wire around the magnet, could you find a way to spin the magnet itself? Actually, Yes! Try this follow-up experiment below.

Bonus Build: Lorentz Spinner

 MATERIALS:

• D Battery
• Electrical Tape
• Copper wire (about 8 inches long)
• Metal Screw
• Neodymium Button Magnet
• (Optional) Watch Battery and an LED light

INSTRUCTIONS:

1. With a piece of insulating electrical tape, attach one end of the copper wire to the positive terminal of the D battery.
2. Carefully place the neodymium magnet on the flat head of the metal screw. (Remember to be careful when using these strong magnets!)
3. *Optional:* Using a small piece of electrical tape, attach the positive arm of an LED light (the longer wire) to the positive surface of a watch battery, as shown in the picture below. Test the setup by pinching the negative arm against the negative face of the battery and turning on the light.
4. Lift and hold the D battery with the positive terminal pointing upward. Hang the tip of the metal screw (with the neodymium magnet attached) from the very center of the battery’s negative terminal. If the screw doesn’t magnetically stay attached to the magnet, you might need to add more magnets.
5. If you are using an LED light, attach the negative face of the watch battery to the bottom of the neodymium magnet, ensuring that the un-taped wire is firmly pinched between the magnet and the battery. The light should turn on!Finally, touch the free end of the copper wire to the neodymium magnet. If nothing happens, try flipping the neodymium magnet(s) upside down and try again. In this experiment, the direction of the magnetic field force is very important!

May The Force be with you…the Lorentz Force, that is!!

INSTRUCTIONS:

1. Unscrew and discard the cap of an empty 12oz water bottle.
2. Create a launch stand for your rocket by securely taping 3 pencils onto the side of the water bottle, making sure that they are evenly spaced. The eraser ends should point upward and rise past the bottle opening by about an inch.
3. Using a funnel, pour 6-8 ounces of distilled white vinegar into the bottle.
4. Place 2 Tablespoons of Baking soda in the center of a dry paper towel. Wrap the paper towel around the baking soda and then fold it up to create a bundle that is thin enough to fit through the water bottle’s opening.
5. Now be sure to grab your adult assistant, and take your rocket assembly outside to a wide open spot!
6. Squeeze the baking soda bundle just inside of the bottle’s neck.
7. Push a snug-fitting bottle stopper or cork into the bottle mouth.
8. Give the rocket a quick shake.
9. Quickly flip the bottle upside down so it is standing upright on the three pencil erasers.
10. Back away fast, or prepare to get splashed!
11. Once your rocket has returned to Earth, you can re-fuel and launch it again and again by repeating steps 3-10!

HOW DOES IT WORK:

Like every object around us, our bottle rocket follows three simple rules of physics. These rules were originally written down by a scientist named Isaac Newton over 300 years ago; and we call them Newton’s Laws of Motion because they describe how an object will move when a force (a push or a pull) acts upon it.

The First Law says that when an object has no forces acting upon it (like an empty water bottle sitting on a table) it will never move all on its own, but remain at rest (like when we pick up the bottle, or knock it over!). On the other hand, an object that is already moving will continue to move in a straight line until a force causes it to stop or change its direction (like how gravity, wind, or resistance from the air influences our bottle rocket’s flight).

The Second Law says that objects of higher mass (that is, heavier objects) require more force to get them to move than do smaller objects. In the case of our bottle rocket, the force that makes it blast off comes from a chemical reaction between the distilled vinegar and baking soda. This reaction is the same one that makes foamy lava in the well-known volcano experiment because it produces a lot of Carbon Dioxide gas bubbles. Since the Carbon Dioxide gas is contained within the bottle rocket, pressure will continue to build up until it is strong enough to actually push out the bottle stopper. But consider this: if we used a larger (heavier) bottle for our rocket experiment, but still had the same amount of pushing force from the Carbon Dioxide, would you expect the rocket to fly as high? Why not?

The Third Law says that for every force, there is another force of equal strength and in the opposite direction. In other words: For every action, there is an equal and opposite reaction. For our rocket’s flight, it is easy to see that there is a lot of action (force) pushing downward from the tail-end of our rocket. But it’s less easy to see that this same exhaust flow creates an upward push on the bottle itself, a reaction force that is called thrust. If we had not flipped the bottle upside-down before it blasted off, the exhaust would have escaped upward and our rocket would have actually flown down toward the ground!!!

Building a Sealed Terrarium

MATERIALS:

• Glass Jar with a lid
• Small rocks (river pebbles, aquarium stones, or even colorful glass beads will work!)
• Wire cloth (fine mesh window screen material is perfect)
• Activated Charcoal
• Peat Moss
• Potting Soil
• Moss, Small Plants, Seeds, or whatever else you want to grow in your terrarium
• Spray Bottle filled with purified water

INSTRUCTIONS:

1. First, we need to choose a suitable jar for our terrarium. A tall bottle with a narrow opening can be a good choice when planting taller plants, but jars with a wider mouth will be much easier to work with. You could even use a cleaned peanut butter jar!
2. Scoop enough small rocks into the jar to create a layer about 1 inch deep. These stones will provide drainage space for extra water to collect in.
3. Cut a piece of wire cloth to cover the layer of rocks in your jar. This wire cloth should allow water to pass through it, but also keep dirt from settling to the bottom.
4. Cover the wire cloth with a thin layer of activated charcoal. You can usually buy activated charcoal at pet stores because it is used to filter aquarium water, just as it will filter the water in our sealed terrarium.
5. Add a ½ inch layer of peat moss, followed by a 1 inch layer of potting soil. The peat moss will provide nutrients for our growing plants, and the potting soil will create a stable foundation for the plant roots to grow in.
6. Now it‘s time to add the greenery! Carefully plant whatever small plants you would like to grow in your terrarium, keeping in mind that each plant will need plenty of room to grow. Do not overcrowd them! For a smaller jar, you may want to only grow a single plant. For larger jars, you could add two or more. You could also add a few plant seeds to your terrarium, if you’d like to watch your plants grow from scratch (be sure to follow any planting instructions on the back of the seed packet).
7. You can also add moss to your terrarium by harvesting small chunks of moss (with a bit of dirt still attached to its roots), and simply tapping it down into the surface of the potting soil.
8. Using a spray bottle, add enough water to thoroughly dampen the surface of the soil. You can also use the spray bottle to clean away any dirt that is sticking to the inside of the jar or to leaves of the plant. Be careful to not over-water your terrarium! Once you see some water dripping into the rock layer, stop watering!!
9. Finalize your terrarium landscape by adding a decorative rock or two, a plastic animal figurine, a tiny garden gnome, or anything else that looks cool next to your plants.
10. Tightly seal your terrarium and place it in a safe spot. Some plants like to have direct sunlight, while other plants prefer to grow in partial shade. However, most plants will grow well when placed near a sunny window.
11. Observe any changes in your terrarium over the next few days. Do you notice water droplets forming on the inside of the jar? Where do you think this water has come from? (The droplets should form only in the morning and again in the evening—but if the droplets are present all day long, you should open the terrarium for a few hours to let extra water evaporate out. If you do not see droplets on the glass, or your plant is beginning to wilt, you may want to add a bit more water.)
12. You should only open your terrarium if your plants look extremely dry

HOW DOES IT WORK:

Sealed terrariums are an easy and fun way to create a self-sustaining garden in a very small space. Plants can survive for a long time in a sealed terrarium after just a single watering due to a special process called the Water Cycle.

Water in the pebble layer at the bottom of the jar will evaporate, or turn from liquid water into vapor, and humidify the air within the jar. Some of this water vapor will cling onto the walls of the jar, creating tiny droplets of liquid water—a step called condensation. As the droplets grow larger and heavier, they will eventually “rain down” onto the plant and soil below in a step called precipitation. This water could be taken in by the plant’s roots, or simply drip back to the pebble bottom and start the cycle all over again. Water that is taken in by the plant is still part of the Water Cycle, because the plant will release this water back into the air in a step called transpiration. Transpiration is a lot like sweating, but for plants! Plants release water into the air through special pores (or openings) in the underside of the leaves.

The Water Cycle allows the water inside your terrarium to continuously hydrate your plants almost indefinitely, but what about the plants outside of a terrarium? How does the Water Cycle affect outdoor plants like grass and trees? Can you identify how water is recycled in nature?

In addition to water, plants need certain nutrients like carbon, phosphorus, and nitrogen in order to grow strong and healthy. In our sealed terrariums, plants must recycle these important nutrients that are initially provided in the peat moss and potting soil. As older leaves fall off the plant, they will begin to rot and decompose, or break apart, releasing nutrients back into the soil to be reused by the plant.

THE MORE YOU KNOW:

Sealed terrariums can keep plants growing for a long time without having to add more water. Incredibly, one such terrarium has been growing for almost 60 years!

In 1960, David Latimer planted a Spiderwort plant inside of a 10-gallon glass container terrarium. It wasn’t until 1972 (twelve years later) that he decided to open the container to add some extra water for the growing plant. He hasn’t needed to open it since then! You can read all about David’s long-lasting terrarium online.

Time to get growing!