Scientific Method: Magic Grow Capsules

Ever played with these?

If you're not familiar with them, they're Magic Grow Capsules. They are small sponge shapes compressed and enclosed in a capsule that dissolves in warm water. Look for them in the dollar section of your favorite retailer, or in the party favor area.

They're fun! And what better way to get your students interested in the scientific method than with something fun?

There are several ways you can go with these guys.


One simple variable to test is the water temperature. The instructions say to use warm water. How long does it take for them to open in warm water, cold water and hot water? A graph comparing the results would probably be appropriate.


Is water the only liquid that works? Try out some other liquids and see if they are equally effective (make sure your liquids are all at the same temperature... you only want to test one variable at a time).


Ask your students to generate other ideas... they will...
-do they still work if the capsules have been microwaved?
-will they work in cold water in the bell jar (air pressure removed)?
-will they work if I bury them in the ground and pour water over them?

A Wall of Scientists

One of the things I incorporated into my science lab was a wall filled with pictures of famous scientists.

I made sure to include the ones we specifically talk about throughout the curriculum as well as scientists with whom the students are familiar and others who I think have contributed to science in a comparably significant way.

I turned my scientists into puppets by attaching a tongue depressor/popsicle stick, so I could use them in that way, if I chose. It also provided a good spot to write their names.

I also added a small piece of magnet tape to the back of each so they could stick to my white board. They were adhered to the wall with tape.


I have several dozen of these guys. And most of them are guys. Which leads to some important discussions...

When you look at the entire history of science, most (but not all) of the work has been completed by white men. We might not like it, and that might not always be the case, but that's the way it was.

I chose my scientists based on the impact they had on the scientific community, in my humble opinion. Others may choose differently.

Molecules: Shapes of Molecules

Determining the shape of molecules can be a tricky business.

For example,
Carbon dioxide (O=C=O) has a central atom (C) with two atoms bonded to it and it has a linear shape.

Water (H-O-H) has a central atom (O) with two atoms bonded to it, but it has a bent shape.


Here’s a demonstration to help you students visualize molecular shapes. And catch your students attention!

Use balloons to represent the number of “things” around a central atom.

As mentioned before, carbon dioxide has two atoms around the central atom, so we tie two inflated balloons together, and voila! The linear molecule is formed:


How about carbon tetrachloride (CCl4) or another molecule that has four atoms surrounding the central atom? Tie four balloons together (I make two pairs of balloons and twist them together) and you’ve got the tetrahedral shape!



Now, back to that tricky water example….

If you draw the electron dot diagram for water, you’ll notice that there are not just two atoms around the central atom, there are also two electron pairs hanging out there. Those need to be accounted for as “things” around the central atom.

So… The oxygen atom in water has four “things” around it that need to be represented with our balloons. Just like with the carbon tetrachloride, I make two pairs of balloons, only this time, I make each pair out of a different color (one color represents the atoms, one color represents the electron pairs).

Twist the two balloon pairs together, and…


Let’s say the green balloons represent the hydrogen atoms…take a look, the green balloons are bent down into a bent shape. The yellow balloons are pushing them down, just as the electron pairs push the hydrogen atoms down!


Cool stuff!

Try it yourself and see what happens if you have 3, 5 or 6 “things” surrounding a central atom.

*********
This activity was presented by C. Lee in a workshop entitled “The End of Boring Biology and Confusing Chemistry” at the 2006 New Jersey Science Teachers Association Convention

Osmosis: Egg-speriment

A classic demonstration of osmosis using a large cell: an egg.

Place an egg in a beaker filled with vinegar for a day or two (over a weekend works well). The vinegar will remove the shell of the egg, leaving the cell membrane. Additionally the process of osmosis will begin with the water found in the vinegar.


Place the egg in a variety of other substances, for one night each.


Vinegar – water flows into the egg, increasing its size.
Water – water flows into the egg, increasing its size (but not as dramatic after a day in the vinegar)
Colored Water – water and dye particles flow into the egg, increasing its size and changing its color
Corn syrup – water flows out of the egg, decreasing its size


You can make the experiment as complex or simple as you wish. You can present this activity as a demonstration, or have students complete it as a lab experiment. Have students measure and record the egg’s dimensions by wrapping a string around the egg’s circumference. Students could also keep track of the volume of liquid that is placed in the beaker and how much remains the following day. After students have recorded data, they can graph it.

Make sure you have antibacterial cleaning supplies ready and available if you take on this lab, especially if you have students working with the eggs – some will break!

Gravity: Weight on Different Planets

Because of the varying sizes and compostion of the planets, each planet has a different amount of gravitational pull. A stronger gravitational pull means that objects are being pulled toward the center of the planet with greater force. The end result is that the object weighs more.

(remember... weight is the measure of gravitational pull on an object, mass is the amount of "stuff" an object is made up of - that doesn't change)

In short:
The larger, more massive the planet, the more gravitational pull, the more something weighs.

The smaller, less massive the planet, the less gravitational pull, the less something weighs.


To help give students a feel for these differences, I created these:

(I've got a whole set, this is just a representative sample!)

I used this calculator (very cool - have your students play around with it to find their weight on other planets) and an Earth weight of 50 g.

The calculator gave me the following weights:
Mercury: 18.9 g
Venus: 45.3 g
Mars: 18.8 g
Jupiter: 118.2 g
Saturn: 45.8 g
Uranus: 44.4 g
Neptue: 56.2 g
Pluto: 3.3 g

I then created these containers, by taping two cups, filled with an appropriate amount of stuff, together.

It's probably not the best container, but it met these requirements:
1 - Light enough to account for the weight on Pluto when empty.
2 - Opaque - I didn't want students to see through the container. I wanted it to look like they were all the same thing, they just weighed different.
3 - I had them on hand.

I believe I mostly used dried peas/beans for the filling. Jupiter may have a few pennies or other more dense weight thrown in to bulk it up!

If you have a dense material on hand (lead, or something of that sort), you could use film canisters, which would be sturdier than my creation.

Air Pressure: How to Blow up a Balloon in a Bottle

Can you blow up a balloon in a bottle?

Go ahead, give it a try. Place a balloon into a bottle (a 2 liter soda bottle works well), leaving a bit sticking out to blow into. Give it your biggest breaths. What happens?

You'll get about this far:


Why can't you get it any more inflated? There's still room in the bottle and the balloon can certainly stretch further than that.

What's wrong?

It's that pesky air pressure again.

The bottle is filled with air. When you start to inflate the balloon, it seals off the opening of the bottle. The air molecules that were in the bottle are stuck in the bottle - they can't get out. And, you're trying to push more air molecules into that space as you inflate the balloon.

Unless you've got lungs unlike any person I've ever known, you don't stand a chance pushing against those air molecules in the bottle.

But, what if you gave those molecules an escape?

Try again, but this time, stick a straw in the bottle with the balloon - the end of the straw needs to be sticking out of the bottle.


Now blow (on the balloon, not the straw!)...

That's more like it!

This post is a part of:

It's...

...a dinosaur coprolite.

What's a coprolite, you ask. A coprolite is fossilized dung. That's right. Dinosaur (in this case) poop that's been turned into rock through the fossilization process.

If that doesn't get the attention of your students - don't tell them until after they've passed it around, felt it, looked at it, etc - I don't know what will!


By the way, I've been told that my coprolite comes from a meat eating dinosaur - that apparently one can identify bits of bone within the fossil. I am not one of those people who can make that identification... I'm just passing along what I've been told.