You know the power of hands-on science when you see it—whether it’s a static balloon that stands your students’ hair on end or an erupting volcano that spews baking soda all over the classroom. The concrete nature of experiments allows your students to observe science at work.

We sat down with Elizabeth Carney and Patty Janes, the editors of two Scholastic student science magazines, SuperScience and Science World, to learn about the most popular hands-on experiments that have graced the pages of their publications. Want to try them for yourself? All you need are everyday science or household items and a classful of inquisitive minds.

### Physical Science: Float-o-Meter

Research Question: How much will water and other liquids propel an object upward?
Materials: Three plastic cups, water, another liquid of your choice (e.g., orange juice, milk), blue and green food coloring, table salt, scissors, permanent marker, metric ruler, modeling clay
Procedure: To make a float-o-meter, cut a straw about 2 to 3 centimeters taller than the plastic cup. Using the marker and ruler, mark centimeters on the straw. Next, roll a clay ball roughly the size of a marble and stick it on one end of the straw. Fill one cup with water and add blue food coloring. Then, fill one cup with salt water and add green food coloring. Fill a third cup with another liquid of your choice.

To see how much water will propel an object upward, put the straw in the blue cup with the clay ball facing down. Measure how many centimeters of the float-o-meter are above water. Have students make a hypothesis about whether the float-o-meter will float higher in salt water and the other liquid. Repeat the procedure with each to find out. (Hint: You’ll have to make all three clay marbles exactly the same size and shape for valid results. Alternatively, you can use one float-­o-meter and move it from cup to cup as you work.)

Concepts at work: buoyancy, measurement
Observations and Conclusions: Buoyancy is the upward force, or push, a liquid makes on an object. The denser liquids will exert a stronger upward force. A liquid like orange juice is denser than water because it contains fruit and sugar. Similarly, saltwater is also denser than water alone because of its dissolved salt. Students will see that the float-o-meter floats higher in saltwater and juice than in water.

### Earth Science: Climate Colors

Research Question: Can the color of your clothes affect how warm you feel outside?
Materials: Three identical drinking glasses, black and white construction paper, adhesive tape, water, thermometer, clock or timer
Procedure: Wrap one drinking glass in black construction paper and secure with tape. Do the same with another glass and white construction paper. Leave the third glass bare (this is your “control” in the experiment). Carefully fill the three glasses with water, and measure the water’s initial temperature. Put the glasses outside in a sunny place or on a windowsill in direct sunlight. Leave them undisturbed for an hour. When the hour is up, take the temperature of the water in each glass. Record your findings. Have students explain what color clothing is best to wear on a steamy summer day or on a chilly winter morning based on their findings.
Concepts at work: temperature, energy, measurement
Observations and Conclusions: Students will find that the glass wrapped in black paper retains the most heat and is therefore the warmest. The glass wrapped in white paper will be the coolest. Students can conclude that it’s best to wear light-color clothes on a steamy summer day and dark-color clothes on a chilly day.

### Life Science: Build a Better "Mouth Trap"

Research Question: How do the different structures of animal mouths allow animals to eat different kinds of prey?
Materials: Letter-size envelopes, three bowls, popcorn, raisins, water, gummy worms, general craft supplies for making mouth traps
Procedure: To make an animal mouth, put your hand inside the envelope. Place your thumb at one end and your fingers at the other. Then pinch the two corners together. Set up animal feeding areas in three bowls—popcorn to represent bugs that fly, raisins in water to represent fish or other prey in the sea, and gummy worms to represent earthworms. Have students decide how their animal mouths will pick up the food, inviting them to use craft supplies to adapt the mouth to serve that purpose. (Students might add double-sided tape to the inside of the mouth to make it easier for their predator to catch “flying” popcorn.) Allow students to visit the feeding stations to test their mouth traps. Challenge them to build better mouth traps by making modifications as necessary.
Concepts at work: structure and function, adaptation
Observations and Conclusions: Students will learn that animals have specialized mouthparts adapted for the food they eat. Conclusions will vary depending on the type of animal mouths that students construct. For example, students might find that long, pointed mouths are best for picking up worms.

### Life Science and Geometry: Shell Shocker

Research Questions: Does an egg’s oval shape serve a purpose? Why isn’t it perfectly round?
Materials: Modeling clay; disposable gloves; four eggs; large, shallow aluminum pan; strong board, such as a thin cutting board; stack of books
Procedure: Divide the modeling clay into eight grape-size pieces. Shape the clay into “cushions” for the eggs by rolling each piece into a round ball and then flattening it into a disc. Use your thumb to make a depression in the center of each disc. Put on a pair of gloves to handle the eggs. Place a clay cushion at the top and bottom of each egg. Place the eggs in the pan, pointed side up. Space them so that each egg will support one corner of the board. Place the board on top of the eggs.

Ask your students to predict how many books they think can be stacked on the board before the eggs crack. (It's probably more than they think!) Then, place the books on the board, one at a time. Continue adding them until at least one of the eggs cracks. Record your observations, and draw conclusions.
Concepts at work: structure, stability, geometry
Observations and Conclusions: Students will observe that the eggs’ structure supports multiple books. Ask students to consider why it’s important for eggs to be able to hold up so much weight. Because chickens and most other birds sit on their eggs to keep them warm, the eggs must support the weight of the chicken without breaking.

### Earth Science: Create a Rift

Research Question: Does molten liquid have the strength to push apart two plates of Earth’s crust?
Materials: Newspaper, piece of cardboard, scissors, ruler, 170-gr. (6-oz.) plastic container of yogurt (with a foil cover), double-sided adhesive tape, two sugar wafer cookies
Procedure: Cover your work surface with newspaper. Cut out an 8-by-8-­centimeter (3-by-3-inch) square of cardboard. In the center of that square, cut a small rectangle measuring 2.5 by 0.5 centimeters (1 by 0.2 inches). Next, cut a small slit in the center of the yogurt cup’s foil top. (The yogurt represents the magma in Earth’s mantle.) Line up the cardboard hole with the slit in the yogurt cup, and use double-sided tape to adhere the cardboard directly to the foil. Next, center the sugar wafers (your “plates” of Earth’s crust) over the hole in the cardboard so that they are parallel to the slit lengthwise. Gently squeeze the yogurt cup. Observe the results.
Concepts at work: plate tectonics
Observations and Conclusions: Students will see that the yogurt rises up through the slit and pushes the wafers apart. Students may conclude that magma can rise up through the Earth’s crust and push portions of plates apart. (A block of cheese wouldn’t be able to squeeze through because it’s solid. But magma’s molten consistency is what makes plate movements possible.)

### Physical Science: Flight Time

Research Questions: What properties of parachutes make them effective for skydiving? Do their shapes play a role?
Materials: Three square bandannas, 11 pieces of string (each 30 cm., or 1 ft., long), three clothespins, a watch or stopwatch
Procedure: Roll up one bandanna (shown in red) and tie a knot in the middle. Fold a second bandanna (shown in yellow) in half diagonally so that it becomes a triangle. Leave the third bandanna (shown in blue) open. Take the knotted bandanna and tie a piece of string to each corner. Knot the loose ends of the strings together. Clip a clothespin over the knotted string. Next, repeat this procedure with the other two bandannas. Raise each bandanna about shoulder height from the floor. Drop each one, and time its fall. Record the results, noting both the time each bandanna takes to fall and its flight path. Based on observations, have students summarize how the shape of each parachute affects the way it falls.
Concepts at work: forces and motion, drag and free fall, gravity
Observations and Conclusions: Students will find that the knotted bandana falls the fastest and the open one falls the slowest. They can conclude that the parachute with the maximum surface area to catch air (the third one that is open) creates the most drag to slow the fall.

### Earth Science: Which Way is North?

Research Question: How can you make a compass to detect Earth’s magnetic field?
Materials: Plastic bowl, water, sewing needle, bar magnet, paper clip, 2.5-by-2.5-cm. (1-by-1-in.) piece of flat Styrofoam, adhesive tape, marker
Procedure: Fill the plastic bowl halfway with water. Magnetize the sewing needle by holding it by its eye end and rubbing the magnet along the needle from its eye to its point about 100 times. (To check that it’s magnetized, hold the point to the paper clip. If the needle doesn’t lift the clip, magnetize it again.) Lay the magnetized needle flat on the piece of Styrofoam, and tape it in place. Next, place the Styrofoam, needle side up, on the surface of the water. Show students which way is north in the room; observe which end of the needle points north. Remove the needle and Styrofoam from the water. Use a marker to write North or N on the end of the Styrofoam that pointed in that direction; do the same for south. Return the Styrofoam to the water’s surface. Nudge it so the needle points in a different direction. Observe what happens.
Concepts at work: magnetic fields
Observations and Conclusions: Students will observe that the needle orientates itself in the north-south direction. Even when nudged, the needle will return back this position. Students can conclude that their contraption has compass-like qualities that can detect Earth’s magnetic field.

### Chemistry: Sunscreen Test

Research Question: How well do sunscreens with different SPF ratings block UV rays?
Materials: Five pieces of masking tape, 5 cm. (2 in.) long; five sealable plastic sandwich bags; marker; UV-sensitive beads (available on Amazon); four bottles of sunscreen (SPF 4,15, 30, and 50)
Procedure: Place a piece of masking tape along the top of each of the five plastic bags. Use a marker to write the following labels on the masking tape: No Sunscreen, SPF 4, SPF 15, SPF 30, and SPF 50. Place a handful of UV-sensitive beads in each of the plastic bags and seal the bags. (UV beads change color when they are exposed to UV radiation. The more UV radiation the beads are exposed to, the more their color changes.) Squirt a dime-size amount of SPF 4 sunscreen onto your palm. Apply it to the outside of the appropriate plastic bag and then wash your hands. Repeat this step with each of the bags. Leave the bag labeled No Sunscreen unprotected. Place all five bags in direct sunlight for five minutes. Observe any changes in the beads’ color.

Concepts at work: energy, chemical reactions
Observations and Conclusions: Students will see that the beads in the bag with no sunscreen change color the most, meaning that UV rays are reaching the beads. The bag coated in SPF 50 will have the least drastic color change. (Note: The amount of color change will depend on the type of beads you purchase.) Students will arrive at the conclusion that sunscreens with higher SPFs are more successful at blocking UV rays.

### Physics: Look Out Below!

Research Question: What factors, including slope angles and surfaces, influence avalanche formation?
Materials: Newspaper; three pieces of cardboard, 22 by 28 cm. (8.5 by 11 in.); one sheet of wax paper, 22 by 28 cm. (8.5 by 11 in.); adhesive tape; ruler; two cups of sugar; eight cups of flour; two cups of potato flakes; protractor; one piece of felt, 22 by 28 cm. (8.5 by 11 in.); glue; 10 small pebbles
Procedure: Lay a few sheets of newspaper on the floor. Tape wax paper to one piece of cardboard to represent an ice-covered mountain, then lay cardboard flat and create four layers of “snow”: First, cover the board with a 2-millimeter (¹/16-inch) layer of sugar. Next, add a 5-millimeter (¹/8-inch) layer of flour. Pack down. Then, make a layer of potato flakes. Finally, add and pack down another layer of flour. Have students line up the protractor with the long edge of the cardboard and slowly tilt it upward holding the short end until the layers collapse and slide. Record the angle. Repeat activity with felt-covered cardboard (to represent a grassy mountain) and cardboard with pebbles glued on (to represent a rocky mountain).
Concepts at work: friction, forces and motion
Observations and Conclusions: Students will find that snow on the waxed-paper surface slides at the lowest angle of incline. The surface with the pebbles has the most resistance to movement. Students should conclude that mountains with rocks, trees, and other objects are less prone to avalanches.