Friday, February 17, 2012

Simple Machines

Learning about simple machines gives your child a little insight into engineering. There are six types of simple machines.

*A lever is a simple mechanism like a board or a beam that rotates around a fulcrum.

*Wheel and axle is a simple mechanism that consists of two connected wheels, which rotate around the same axle.
*An inclined plane has no moving parts. Chutes, ramps, slides, and blades are examples of inclined planes.

*A wedge is an inclined plane that is used for lifting, holding, or separating objects.

*A pulley is a simple machine that uses grooved wheels and a rope to raise, lower, or move a load.

*A screw is a simple machine that holds things together.

Help your child execute experiments with each simple machine.

Here are two to get your started:

Messages on a Pulley

A PULLEY lets us change the direction of the force we use to do work.

Question: Can you use a pulley to help you send messages across a room?

Materials: 2 thread spools, 40 feet of string, 2 round pencils, paperclips, message

1. Put the pencils through the thread spool centers. Tie the ends of the string together to make a loop. Have one person hold the ends of one pencil (allowing the spool to turn freely. Have one person hold the other spool. Wrap the string around the spools to create a pulley system.
2. Write a message; attach it to the pulley with a paper clip. Have a third person pull the string to move the message.
1. Did you message travel across the classroom by pulley?
2. Is that what you thought would happen?
3. What did you learn?

Count the Turns
A SCREW is used to hold things together. It has a line that goes around it that is called THREAD (actually a twisting inclined plane).

Question: What type of screw takes more turns to go into a block of wood - one with more or less thread?
Materials: Wood block, same size screws with different sized threads, screwdriver, and masking tape

1. Wrap a screw driver handle with a piece of masking tape. Make a mark on the tape. YOU WILL COUNT ONE TURN EACH TIME THE MARK COMES BACK TO THE PLACE IT STARTED.
2. Place the screwdriver into the slot of one screw. Watch where the mark is and start turning the screw to the right.
3. Count how many turns it takes to get the screw all the way into the wood.
4. Repeat for the other screw or screws.

1. Which screw took more turns to go all the way into the wood?
2. Is that what you thought would happen?
3. What did you learn?

Saturday, February 4, 2012


A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth. When pressure builds up, eruptions occur. Gases and rock shoot up through the opening and spill over or fill the air with lava fragments.

There are more than 1500 active volcanoes on the Earth. There are at least 80 under the oceans.

Here are two volcano experiments:

Baking Soda Volcano

· 6 cups of flour
· 2 cups of salt
· 4 tablespoons cooking oil
· 2 tablespoons of baking soda
· dishwashing detergent
· food color
· vinegar
· warm water
· baking dish or pan

First, make the cone of the baking soda volcano. Mix 6 cups flour, 2 cups salt, 4 tablespoons cooking oil and 2 cups warm water. The mixture should be smooth and firm. Add more warm water if needed.
Stand the soda bottle in the baking pan and mold the dough around it into a volcano shape.
*Don't cover the opening or drop dough in it.
Fill the bottle most of the way full with warm water and a bit of red food color.
Add 6 drops of detergent to the bottle contents.
Add 2 tablespoons of baking soda to the contents.
Slowly pour vinegar into the bottle and watch the eruption!

Why does this happen? The red lava is the result of a chemical reaction between the baking soda and vinegar. In this reaction, the carbon dioxide gas is produced; pressure builds up inside the plastic bottle until the gas bubbles out of the volcano. This is a good representation of what happens in real volcanoes.

Soda Bottle Volcano
· roll of mint Mentos (type of candy)
· clear 2-liter bottle of Coke (diet works better)

Go outside to an area where you have a lot of room. This experiment is messy! Open the bottle of soda carefully. Position the bottle on the ground, so that it will not tip over.

*Diet soda works better than regular soda. Plus, diet doesn't leave a sticky mess.

Unwrap the roll of Mentos. The goal is to drop the Mentos into the bottle at the same time, which is very tricky. One method is to roll a piece of paper into a tube just big enough to hold the loose Mentos. Put a card under the roll and on top of the bottle top, so you can pull the card and the candies will just drop in at once.

Drop all of the Mentos into the bottle at the same time and then move out of the way just as quick as you can and watch the eruption!

Water molecules attract, linking together to form a tight mesh around each bubble of carbon dioxide gas in the soda. When you drop the Mentos in the soda, the gelatin and gum arabic from the dissolving candy break the surface tension. Each Mentos candy has thousands of pits on the surface. These tiny pits are called nucleation sites, perfect places for the carbon dioxide bubbles to form. As soon as you drop the Mentos in the soda, bubbles form all over the surface of the candy. Couple this with the fact that the candies are heavy and sink to the bottom of the bottle and you are just asking for an explosion. When all this gas is released, it literally pushes all the liquid up and out of the bottle in an amazing blast.