Growing Microbes

Materials: clean jar, unflavored gelatin, cotton swab, water, patience

Boil 1/2 cup water, then sprinkle in 4 envelopes unflavored gelatin.  Dissolve it and pour it into the jar.  Set it on its side.  Let the extra pour out.  Put on sneakers without socks and go play outside.  Three hours later the gelatin will be hard and your feet will be smelly.  Take the swab and rub it good in between all your toes.  Now carefully brush the gelatin with the cotton tip in long strokes.  Close the jar and put it in a warm dark spot.  Maybe keep it warm by wrapping it up in a big bath towel.  Leave it in the dark for 4 days.  Go wash your feet.   Inside your shoes it's dark, warm and damp - perfect for microbes!  And they grow and grow.  Your jar is pretty much the same.  The gelatin is what the microbes are eating.  It is called a growth medium.   After 4 days, you'll be able to see grooves in the gelatin.  The microbes are eating it.  When you open it, you'll smell something much worse than smelly feet.  It smells horrible.  Really horrible!  You might even start gagging.  Don't touch inside the jar.  Fill it with hot water, let it soak and then recycle the jar.  Wash your hands really well.


A Stronger Magnet

Have a grownup scrape about one inch of the covering off the end of two bell wires.  About a foot from one that end of each wire, wrap the wire evenly around a large nail.  Make as many turns as you can.  Tape the wire at both ends of the nail to hold the wire in place.  Attach the bare ends of the wire to the two battery posts on a No. 6 dry cell.  Now holding the two nails together in one hand, test your magnet.  How many paper clips can it pick up?  Can it pick up heavier metal things?


Now unhook the wires from the battery.  Take the long end of the wire and wrap a second layer of wire around each nail.  Tape the ends in place.  Hook the wires to the battery and test these new magnets.  How do they compare?

 Now unhook the wires from the battery.  Take the long end of the wire and wrap a third layer around BOTH nails together.  How does this compare to the other magnets you made?  What have you discovered?


Dry Ice Fun

Make some Kool-Aid and put it into a clean, empty, plastic milk jug.  Fill it about 3/4 full.  Using tongs, place a few small pieces of dry ice into the Kool-Aid mix and recap the bottle.  Let each Cub see the reaction that takes place.  While they observe this, you will need to monitor the jug to make sure the gas pressure doesn't build up too much.  Occasionally, open the jug and let some of the gas escape.  Be sure the Cubs see this, as it's a visual (and audible) treat to see it expand and contract the jug. 

 Wow!  What's happening here?  After dry ice is added to the Kool-Aid, it starts looking pretty weird!  What is dry ice?  It's frozen carbon dioxide, which is normally a gas.  Frozen carbon dioxide doesn't melt into a liquid (at least not on this planet!) but evaporates directly into a gas.  That's why it's called dry ice.  It's lots of fun to watch, but you should remember to never touch it.  It causes bad burns and is quite dangerous.

 So, what is it doing in the Kool-Aid?  It's sublimating which is a fancy word for "melting into a gas."  In addition to making the bottle bulge, its also putting gas into the Kool-Aid, so the Kool-Aid will be a bit fizzy when we drink it.  That's pretty much how they make soda pop, too!  Then offer the drink to the Cubs but be sure that NO ICE CHUNKS go into the cups!

Bubble Gum Fun

Pass out 2-4 pieces of bubble gum per Cub.  Ask them not to open them until you say its OK.  Read this: "What is bubble gum?  Why does it do what it does?  It's a type of PLASTIC! Plastic stuff is made up of long chains of molecules.  When you blow a bubble, you are really just moving the chains around and making them stretch into a new shape.  Today we would like you to experiment with the gum - try to blow bubbles, stretch it out, have fun!  At the end, though, we want you to leave your gum in the trash basket.  OK - open the gum and chew away!

Removing an Egg's Shell Without Cracking It

Materials: 1 Ziplock sandwich bag, 1 uncooked egg, 16-fluid oz. white vinegar, 1 glass

1.       Put the egg in the bag.  Add enough vinegar to completely cover the egg, or enough to half-way fill the bag.

2.       Close the bag, removing most of the air.  Observe the egg, noticing specifically the bubbles on the shell.

3.       Turn the bag so that the egg is in one corner, and place this corner into the glass.

4.       Let the egg sit overnight.  In the morning it will feel soft, this is because the vinegar has dissolved most of the hard part of the shell.  Let the egg sit for 2 more days in the vinegar, to assure that the shell has been dissolved.

5.       Over the sink, pour the vinegar out of the bag.  Under a trickle of water, wash the egg gently to get all traces of the shell off.

 What happened?  The shell was dissolved by the vinegar, but the membrane underneath wasn't.  The membrane helps protect the egg.  Observe how the shelled egg feels.


The Power of Paper

This shows what makes corrugated cardboard boxes strong.  Take a sheet of white paper and crease it 1/4" from the edge.  Continue folding and creasing the paper in 1/4" folds accordion-style.  Make two paper columns by rolling a sheet of paper around a can and taping the ends together.  Remove the can(s).  Stand the two columns on end 4" apart.  Set the pleated sheet across the tops.  Place the can on top of the pleated sheet.  Wow!  An engineer discovered that pleating paper gives it more strength.


Magnetic Personality

You'll need: steel wool pad, bar magnet, two sheets white paper, dull scissors, magnifier

1.      Lay one sheet of paper on a flat surface and cut the steel wool pad into fine little threads.

2.      Put the bar magnet down on the table and put the second piece of paper over it with the magnet in the middle.

3.      Carefully pour the steel wool threads onto the paper over the magnet.

4.      Lightly pound the table near the thread-covered paper.

5.      Watch the threads go!

 The threads will end up in a roughly circular pattern - the magnetic field.  Notice there are more threads at the magnet's poles where the force is greater.  The threads are thinner near the center.  This resembles the magnetic field that surrounds the planet Earth.


Hair Raising Experiment

You'll need: balloons

1.      Inflate the balloons.

2.      Rub them against your hair or against a woolen sweater.

3.      Bad hair day?

4.      Then put the balloons against a wall.



Solar Water Heater

You'll need: glass jar filled with water, magnifying glass, thermometer

1.        On a sunny day, put the jar of water in the sun.  Place the thermometer in it and take the initial temperature reading.

2.        Focus the magnifying glass on the water.  Twenty minutes later, take another temperature reading.

3.        Remove the magnifying glass and take another reading twenty minutes later.

 Explain that the magnifying glass concentrates the sun's rays on the water, something like a solar furnace.  After removing the magnifying glass, what happened to the water temperature?  Why?



Materials: Construction paper, brad, penny, straw, hole punch, scissors, pencil

Directions: Cut paper into a 6" x 6" square. Draw diagonal lines from corner to corner. Using the penny, trace a circle in the center. Cut the diagonal lines to the edge of the circle in the center. Punch 4 holes in the pinwheel, to the right of each cut close to the edge, and one in the center. Punch a hole through the top of straw using hole punch. Fold each corner, without creasing, to the center and fasten together with the brad. Push the brad through the hole in the top of the straw and loosely fasten the brad. Hold in the wind!

Rain Gauge

Materials: Plastic medicine bottle, permanent marker, ruler (I have also seen these made with skinny olive jars)

Directions: Mark off regular intervals onto the medicine bottle using the ruler and indicate each with a mark of permanent marker. Place outside where it won't be knocked over. After each rain, see how much rainwater filled the gauge.

Making A Switch
Sam Houston Area Council

Collect a battery and a light of the same voltage (electronic supply stores have these), electrical wire, two brass paper fasteners, a paper clip and an index card. Use a hole punch to punch two holes in the index card, about 1" apart. Put a brass paper fastener through the paper clip and then through one of the holes in the index card. Put the other fastener through the other hole. Cut three short lengths of electrical wire and remove a small amount of insulation from each end. Attach one wire to the ends of one paper fastener and the battery, one wire to the battery and the light, and the final wire to the light and the ends of the second paper fastener. Show the boys the circuit and demonstrate how the light comes on when the paper clip is positioned to touch both paper fasteners. Tell them that the paper clip is like a switch. When it touches both paper fasteners, the circuit is complete and the light will come on. When it is not touching, the circuit is not complete and light will not come on.


Rocket Pinwheel

Materials: Wooden pencil with an eraser on one end Sewing pin Round party balloon Flexible soda straw Plastic tape

Method: 1.Inflate the balloon to stretch it out a bit.

2. Slip the nozzle end of the balloon over the end of the straw farthest away from the bend. Use a short piece of plastic tape to seal the balloon to the straw. The balloon should inflate when you blow through the straw.

3.Bend the opposite end of the straw at a right angle.

4.Lay the straw and balloon on an outstretched finger so that it balances and mark the balance point. Push the pin through the straw at the balance point and then continue pushing the pin into the eraser of the pencil and finally into the wood itself.

5.Spin the straw a few times to loosen up the hole the pin has made.

6.Blow in the straw to inflate the balloon and then let go of the straw.


The Amazing Electric Lemon

Clean galvanized zinc nail

2 ' insulated copper wire

X-Acto or utility knife

Small flashlight bulb

Electrical tape

Large lemon

Clean penny

Cut your wire into two 1' sections and strip off one inch of insulation from all four ends of wire. Attach one end of each wire to the light bulb so that one end is touching the metal threads on the sides and the other is touching the metal cap on the bottom. Being careful that the two wires do not touch, secure them with electrical tape.

Cut two small notches into opposite sides of the lemon with your knife. Insert the penny halfway into one notch and the zinc nail halfway into the other. Be sure that the penny and the nail do not touch. Take one of the free ends of wire and tape it to the nail.

Now when you touch the remaining exposed end of wire to the penny, the flashlight bulb should give off a faint glow.

Try this same experiment with different fruits, such as oranges, grapefruits and limes. Rate the amount of light given off by each fruit battery. The more acidic the fruit, the brighter the light.


Lemon Writing

Materials: lemon, bowl or cup, skewer stick or toothpick, iron, paper

Cut the lemon and squeeze some lemon juice into the bowl or cup.  Dip the stick into the juice, and write whatever you'd like on the paper.   You probably won't be able to see anything though.  Wait for the juice to dry.  Have an adult iron the paper lightly, and the lemon writing will appear!



Materials wax paper, crayons or candles, scissors or cheese grater, iron, hole punch, string or yarn.

Lay down a piece of wax paper.  Shave or grate wax from the crayons or candles on top.  Cover the shavings with another piece of wax paper and iron the two sheets together.  Cut out various shapes, punch a hole in the top and hang in a window.