Homemade Gears

In this week's book, some of the characters had body parts made of tiny, intricate gears. Today we'll make our own gears and learn a little about how they work!

Gears are wheels that turn each other. To start out, make some wheels by cutting different size circles in cardstock. (We traced ours from the bottom of cups, but a compass would be even better because you'd know the exact center of the circle.)

Most gears have teeth to help them spin each other. Take another piece of cardstock and fold it into a fan. Make the folds as even as possible so your teeth will be as even as possible.

Next, cut the fan into strips. These will be the teeth of your gears. Cut a small notch down the center of each strip of teeth, then slide this notch over the edge of your circle. You will probably need multiple strips of teeth to go around even your small circles. Try to space out the teeth as evenly as possible.

When your gears are finished, put a pin through the center and stick them to a corkboard. Now you can make a gear train--a series of gears that turn each other! Watch your gears as they turn. The one you're pushing is the driver gear, and the others are follower gears. Do they all turn the same direction? Can you predict what direction they'll all turn if you change the direction you're turning the driver gear? Is it easier to turn a small gear or a larger gear? Which one goes around the fastest?

For more great info on gears, check out this video or this website. Have fun!

Weight and Mass

I have a feeling Ramona Quimby grew up to be a scientist. Here are a couple of reasons why:

If Ramona drank lemonade through a straw, she blew into the straw as hard as she could to see what would happen.

"Ramona, what did you have to go and do a thing like that for?" Beezus demanded of her little sister, who was playing with her doll Bendix.
"To see what would happen," answered Ramona.
[After Ramona drops all the eggs, shells and all, into the cake batter and starts the mixer.]

Ramona knows that she doesn't just have brown eyes, that she really has brown and white eyes. She likes lizards, even imaginary ones like Ralph. She pretends to weigh herself at the grocery store (and proclaims that she weighs "fifty-eleven pounds.")

In Ramona's spirit of science and curiosity, we're going to learn about weight and mass today. What's the difference?

Mass is how much matter is in an object. You'll have the same amount of mass wherever you go or whatever you're doing. It changes a little any time matter goes in or out of your body--when you eat or go to the bathroom, and even a tiny bit when you breathe in and out. Because air and gas have mass too! If you measure with grams or kilograms, you're measuring mass.

Weight (often measured in pounds, but usually not "fifty-eleven pounds") is how much gravity is pulling on an object. It's related to mass, but they're not exactly the same. The more mass you have, the more you'll weigh, because gravity will pull on you more. But if you went someplace with less gravity, like the moon, your weight would change even though your mass stayed the same! You can find a fun weight calculator here that tells you your weight on the moon and many other planets. Try to predict before you put the number in--where would you weigh the most? Where do you think you'd weigh the least?

Now for the activity. You can make a balance easily by stringing two cups to each ends of a hanger. Put the hanger over a string or dowel, then start measuring! Use a small object like a paper clip as a unit of measure (paper clips actually have a mass of about 1 g) to find approximate masses of things like ping pong balls and pebbles. (This is a good one to demonstrate that greater volume doesn't always equal greater mass.) Gravity will pull harder on whichever side has the greater mass and the greater weight.

Have fun measuring weight and mass!

Magnifying Glass Magic

In The Magic Half, Miri uses a magic lens to put things right. In this science activity, we'll explore with a not-so-magic lens called a magnifying glass, then use our lens to turn a picture upside-down and backwards!

Materials needed:

• magnifying glass
• white piece of paper or card stock
• computer or TV screen in a dark room

First, examine your magnifying glass. As you feel from one edge of the lens to the other, it bumps out. This means it's a convex lens. (If it dipped in, it would be a concave lens. An easy way to remember this is that a concave lens is shaped sort of like a cave.) Use your magnifying glass to get a better look at book covers, sand, your hair--everything around you! Notice that the magnifying glass only works when you hold it fairly close to the object you're trying to observe.

So why does it make things look bigger? Because the lens is bending the light from whatever you're looking at. And since it's a convex lens, it makes the light bend outward, and your eye sees a bigger image. You can find more information about how lenses work at sites like Optics for Kids and Activities in Optics.

Now for our magic trick. Take your magnifying glass and a piece of white paper or cardstock to a dark room with a TV or computer screen in it. Hold the paper about 3 feet from the screen with the magnifying glass against it. Now slowly move the magnifying glass away from the paper and toward the screen. (All three things--screen, magnifying glass, and paper--should be parallel to each other.) When you get it to just the right distance, you'll see the image from your screen projected on the paper--but upside-down and backwards. It's magic! :)

If you're not satisfied to leave this as a magic trick (and why should you be?), there's a great explanation of how it works here. This is the same "magic that's happening in projectors and even inside your own eyes! (Yes, your eyes have convex lenses too!)

See what other great (and preferrably safe) things you can do with your magnifying glass!

The Six-wise Symmetry of Snowflakes

This week's book, Anne Ursu's Breadcrumbs, is full of snow. In fact, Hazel watches the snow fall in the very first scene and admires its "perfect geometric patterns." So let's take a closer look at the geometry of snowflakes!

Most snowflakes have hexagonal symmetry, which means that there are six lines you could draw through the center where one side would be the mirror image of the other. (Or six ways you could fold it so the sides would overlap each other.) Try it out on any of the snowflakes in the picture! Three of these lines will be along the "arms" of the snowflake, and three will be between the "arms." Check out some more beautiful photographs of single snowflakes here and look for the lines of symmetry in each flake.

Follow this link to learn how to make paper snowflakes of your own that actually have hexagonal symmetry. You can use any piece of square paper to start, but origami paper is perfect for this one since it's a great size and usually has a white side and a colorful side. (If you don't have the supplies or you're not feeling crafty, you can even design a virtual snowflake here.)

Once you've gotten the process down, challenge yourself! Can you picture or sketch the snowflake you want to make, then fold and cut to make it happen? Can you fold and cut, then draw a prediction of what your snowflake will look like before you open it?

Like all good scientists, doing one experiment might just make you ask more questions. Here are some questions you might have, and a good place to find the answers:

Do all snowflakes have hexagonal symmetry, or are there other types? Answer here.
Does artificially-made snow have hexagonal symmetry and pretty snowflakes? Answer here, then scroll down to "Artificial Snow."
Why are snowflakes symmetrical anyway? And how do the arms "know" how to match each other? Answer (sort of) here.

Exploration and Observation: Balloon Rocket Launch

In Cosmic, Liam gets to go on "The Biggest Thrill Ride in the History of the World"--a trip to the moon! Let's make some indoor rockets and see if we can launch them all the way to the ceiling.

Materials needed: fishing line or string, drinking straws, balloons, shuttle picture, masking tape

1. Prepare the launch site. String fishing line from the ceiling--more than one line, if you want to launch more than one rocket at the same time.

2. Prepare your rocket. Color and decorate your shuttle, then cut it out and attach a straw to the back with masking tape. Blow up a balloon, but don't tie off the end! The air in the balloon is the force that will launch your rocket.

3. Prepare for liftoff. Attach your balloon to the straw with masking tape (keep pinching the end!), then slide the straw over the bottom end of the fishing line. Hold the bottom of the fishing line against the floor so it forms a straight vertical line. (If you allow slack in the line, the rocket won't launch as high.)

4. Launch! When your line is tight, count down and launch your rocket! Then perform experiments to answer the following questions, and see if you can come up with some questions of your own:

Does the rocket launch higher if I put more air in the balloon?
How would I design a rocket that would launch even higher? What changes could I make to this design--what could I add, and what could I take away?
What happens if I launch the rocket without sliding the straw over the fishing line?
Can I attach other things (paper clips, paper people, etc.) and still launch it all the way up the line?
How many times can you use the same balloon before it loses some of its launching power? Why do you think this happens?

Happy launching!