Simple Machines, Part II

This week at Catalina we'll be exploring another Simple Machine! This time we'll test the effectiveness of an inclined plane (one of 6 simple machines) using marbles and tracks. This is an old favorite with my older students, as you may have seen in a previous post about Rube Goldberg machines. For preschoolers, a very simple 5-minute introduction to slope and velocity (i.e. how fast the marble goes) is enough to get them started building their own marble tracks. You'll be surprised at how adept they are at making these.

There is no shortage of materials you can use to build your own marble tracks. Here are some materials you may find at home:

• hotwheels tracks (these make excellent tracks for any age and are easy to put together)
• PVC pipe, any diameter or length
• outer casing of fluorescent light bulb tubes (I found someone at Ace Hardware who dug some up for me, as they're not usually sold on the shelf)
• wood cove moulding (found at home improvement stores, about $0.70 per linear foot for standard pine)
• cardboard boxes, building blocks, foam blocks, or cardboard bricks (for propping up the track and creating different slope grades)

If you use wood cove moulding, you can cut these to several different lengths to make it more interesting. Glue two equal-length sides together, side by side, to make a nice concave track for the marble, and that will also sit flat on the bottom. I used regular Elmer's "Glue All" to glue the pieces together and then clamped them together while they dried.

Try these out and have fun!

Simple Machines

This week we are building catapults using a simple machine: a lever. Here are the materials you need to make one at home:

yardstick
1 and 1/2" PVC pipe (approx. 3" section)
rubber band (optional)
dixie cup
ping pong ball

The yardstick serves as the "lever" and the PVC pipe serves as the "fulcrum." Place the PVC pipe under one end of the yardstick. String the rubber band through the middle of the PVC pipe, then wrap each end around the end of the yardstick to attach the PVC pipe to it. Then slide it down toward the middle of the yardstick. (You don't really need the rubber band, but its purpose is to help keep the fulcrum in place as you use the lever. Just slide the rubber band with the fulcrum back and forth down the yardstick to adjust the placement of the fulcrum.)

Use a glue gun or strong tape to attach the dixie cup, open side up, to one end of the yardstick. Now the fulcrum (PVC pipe) should be on the underside of the yardstick and the dixie cup should be on the top. This is for holding the ping pong ball.

Now you're ready to play! When you put the ping pong ball in the dixie cup, that is called the "load." Use your hand or foot to push down quickly on the other side of the yardstick (this is called the "effort") and see how far your ping pong ball flies through the air!

Practice placing the fulcrum at different locations along the yardstick to see how that changes the distance your ping pong ball travels. What is the best placement for the fulcrum?

Rube Goldberg Machines at Camden

This Wednesday in Weird Science we will be exploring Momentum! I am bringing back a very popular activity that I've done in the past with the kids. We will break up into 2 - 3 person groups and build marble tracks using different building materials. The students will be challenged to design a marble track that keeps their marble rolling for the longest period of time. Then, we will spend some time engineering the track materials so that all the components (groups) might work together in one large Rube Goldberg machine! If you don't know what a Rube Goldberg machine is, here is a fine example on youtube that the band OK GO used for one of their music videos. Your kids might enjoy this:

Of course, the ones we design won't be nearly this complex, but fun nonetheless!

Pizza-Box Solar Ovens

Pizza-box solar ovens are perfect projects for elementary school kids and older! Next week I'll be making them ahead of time for the preschool group so that they can melt candles inside them and watch the temperature rise as we put them out in the sun. In the past, my solar ovens have reached temperatures around 200 degrees F. They don't get too hot, but hot enough to melt things! I haven't tried cooking anything in them-- I would want the temperature to be at least 350 degrees F for that. So I need to refine the design a bit to reach that goal.

If you are interested in making a pizza-box solar oven, here is a great youtube video that shows you how to do it step by step. Enjoy!

How to Make a Pizza-Box Solar Oven

Bubblemania!

Well, it's time for one of my favorite activities with my preschooler Weird Scientists! I have the kids make their own bubble wands and have them try out different shapes to see if it "changes" the shape of their bubbles. We also do a time test, comparing bubbles from a day-old solution to one we made on site. Did you know that pipe cleaners can make excellent bubble wands? Another favorite is a long piece of PVC pipe with a cord loop attached to the end. One end of the cord loop slides up and down the PVC pipe. After you dip the cord in the bubble solution, pull it out and carefully slide the one end of the cord up the pipe toward your hand. Swing it gently around in a semi-circle around you to make a giant bubble, then gently slide the cord closed again to close the bubble and release it.

Usually I like to make our bubble recipe with home-grown glycerin from my husband's former biodiesel-brewing days. However, this time I'm using another tried and true recipe that makes wonderful bubbles (especially if you make it a day or two before you want to use it):

Ingredients:

6 cups of distilled water

1 cup corn syrup

2 cups Dawn dish soap

To prepare:

Stir together water and corn syrup.

Add the Dawn dish soap and stir very gently, without making bubbles.

Henry's Birthday Brew!

Here are some of the fun experiments we did yesterday, inspired by a young Mr. Henry who turned 8 years old. Happy Birthday Henry! These are all experiments you can do at home, with materials straight out of your kitchen (or bathroom) cupboard.

The Famous Mentos Geyser Experiment

Materials:

• 2-liter of Diet Coke (and other varieties of soda to test out for fun)
• 1 roll of mint-flavored Mentos (allow approximately 1 roll for each 2-liter bottle)
• 1 piece of scrap paper

Method:

• Do this outside!
• Open the 2-liter bottle and place it somewhere where it won't fall over. Also keep it several feet away from any furniture or other materials that you don't want covered in Diet Coke.

• Roll up the piece of paper into the shape of a funnel that will allow the Mentos to drop through it, into the 2-liter bottle.
• Open the Mentos and drop them, all at once, through the funnel into the bottle.
• Stand back!

Home-made Lava Lamp

Materials:

• One empty 2-liter bottle leftover from the Mentos Experiment
• Approximately 10 oz of tap water per 2-liter bottle (less for a smaller bottle; this does not need to be an exact amount. You simply need a layer of water on the bottom of the bottle)
• Enough vegetable oil to fill the remainder of the volume in the 2-liter bottle (or whatever size bottle you are using), after the water is added.
• Food coloring
• Alka Seltzer tablets (at least 2 per 2-liter bottle)
• Funnel

Methods:

• Pour the tap water into the 2-liter bottle using the funnel.
• Tilt the bottle on its side and use a funnel to pour in the vegetable oil, filling it to the top of the bottle (tilting helps prevent too much mixing of the oil and water).
• Add a few drops of food coloring.
• Observe where the food coloring goes when you add it to the bottle. 
• Add 2 tablets of Alka Seltzer to the bottle, and Voila!
• Feel free to add more tablets of Alka Seltzer to keep the action going whenever you want to!

Fabulous Foam

Materials:

• 3/4 cup Hydrogen Peroxide (3% is standard; 6% or greater is available at salon stores and works even better!)
• 2-liter bottle or similar size bottle
• Approximately 1 tbs of yeast
• Approximately 3 tbs of warm water
• Cup for mixing yeast and water
• Squirt of dish soap
• Funnel

Methods:

• It's best to do this in the kitchen sink or outside.
• Use funnel to pour hydrogen peroxide into 2-liter bottle.
• Add a squirt of dish soap to bottle.
• Add a few drops of food coloring.
• In separate cup, mix yeast and warm water until yeast is dissolved or not lumpy.
• Add yeast mixture to 2-liter bottle and watch the reaction!
• Observe the temperature of the bottle as the foam is produced. The yeast is a catalyst and causes the extra oxygen molecule in the hydrogen peroxide to be released as foam (made even more foamy by the dish soap). This is an exothermic reaction (heat is produced); you should feel the heat increase as the reaction occurs!

Frankenstein's Glove

Materials:

• One latex glove
• Approximately 1 cup of vinegar
• A few tablespoons of baking soda (this is an imprecise experiment!)
• One jar or cup wide enough that the glove will fit over the top securely.

Methods:

• Pour the vinegar in the jar or cup.
• Pour the baking soda into the latex glove, filling the fingertips.
• Secure the glove over the top of the cup.
• Lift the fingers of the glove so that the baking soda falls out of the fingers into the jar or cup.
• Watch the glove come alive as carbon dioxide is produced from the reaction between the baking soda (sodium bicarbonate) and the vinegar (acetic acid).

Coming this week to Catalina Day School: A scientific treasure hunt!