Now let’s use the scientific method to discover a couple of things about pendulums. Before we start, I need to tell you two new terms. One is constant variable and the other is changing variable. A variable is a part of your experiment, like the coin in the Underwater Presidents experiment. If it is a constant variable, it stays the same for every trial of that experiment.

For example, we always used the same penny in the Underwater Presidents. Those variables never changed. A changing variable is what you change for each trial. It is often what you are testing for; “If I change this, what happens to that?”

For example, in the Underwater Presidents experiment, if we tried water in the dropper, then we tried vegetable oil, then corn syrup; the changing variable would be the liquid we are using in the droppers. When you do an experiment you have to try very hard to keep all variables constant except for the one you are testing for. If you don’t keep all but one variable constant, you won’t know why you are getting the results you’re getting. If you change the size of the coin, and the type of liquid with the Underwater Presidents experiment, you will have a hard time knowing if it’s the change of coin or the type of liquid that’s causing more or fewer drops on the coin. Let’s try the following experiment and see if this becomes clearer.

What you need:

• String
• Weight of some sort
• Tape
• Timer (or a watch with a second hand)

A constant variable is one that does not change from trial to trial. A changing variable is the one variable you are testing for. It does change from trial to trial. One of the most difficult things to do in scientific research is to know what all of your variables are and to keep all but one variable constant.

In these pendulum experiments other variables were the temperature of the room, the humidity, the spin of the Earth, the design of the pendulum, etc., etc. We made an assumption that all those variables remained constant and didn’t really matter to our experiments. In this case, that’s a safe assumption but sometimes you can’t be too sure!

Constant and changing variables are around you all the time. What would be some variables in your breakfast? Which ones change from morning to morning? Which ones stay the same? What about some variables in the car? Which are constant and which are changing?

Let’s take a look at how to handle these questions:

What you need:

• String
• Several weights of some sort (a bunch of the same kind of washer works very well)
• Tape
• Scale (optional)
• Timer (or a watch with a second hand)
• Use the same pendulum set up you used for “The Size of the Swing” experiment.

The first step of the scientific method is observation. In my opinion, this is the most important and enjoyable part of the scientific method. Observation is the skill of “seeing” things that are there, “seeing” things that aren’t there and “seeing” things that should be there.

Observation is the skill that separates scientists from super scientists. Einstein, Galileo and Newton, for example, were fantastic observers. They were able to “see” beyond and through what other people were able to “see” before them in order to get to deeper truths inside science.

I’m putting “see” in quotes because there’s more to observing then just seeing with your eyes. First, you need to detect something. You can use your eyes, ears and nose to detect things. You can also use instruments like telescopes, microscopes or prisms to detect things. Somehow, something needs to come to your attention.

But that’s not all there is to observing something. Next you need to use your knowledge and your intuition, to fully observe what’s happening. When you look up into the night sky you might only see bunches of little white dots, but a trained astronomer would see stars of different magnitudes, galaxies and constellations. The astronomer’s knowledge allows her to “see” more. This is why I think observation is so much fun.

Observing allows you to know things and knowing things allows you to observe more things! You can’t help but get smarter if you spend your time observing! In this lesson, we’re going to spend time becoming better observers. Try this activity.

We’re going to build on the idea from the last experiment by adding a color component to the experiment.  Here’s what you need to do:

You need:

• Paper
• Pencils
• Volunteers

This is an excellent exercise in observation. I highly recommend finding other pictures in books and magazines and doing this several times. It’s a great way to get better and better at the skill of observation. It’s also a nice way to pass the time in a waiting room!

You need:

• The question sheet below
• Paper
• Pencils
• Friends

Observation is a skill just like any other skill and it can be exercised and improved over time. Being a good observer means always keeping your eyes open and being aware of what’s around you. With good observation skills and knowledge the world becomes just that much more wonder-filled!

Here’s an activity you can do to hone your observation skills:

You need:

• 5 to 10 small items (pencils, crayons, balls, eraser, toy cars, buttons, whatever is handy)
• A handkerchief or napkin large enough to cover all the items.
• Some friends

Fish in the can saws wild apples dog car sidewalk tree. Shirt the table carpet in the floor roof cloud. What? What do you mean I’m not making sense? I’m using simple English words. Oh, I see. I must not be communicating.

Believe it or not, communication is not as easy as it seems. In this lesson, I’m hoping to show you that hearing what someone is saying, and saying what you want someone to hear is quite a skill. A good skill for life and a vital skill for science.

In science, the ability to tell someone what you did, how you did it, and what happened after you did it, is a key skill in sharing science information. Scientists from around the world share information and their measurements and details of what they did must be very precise. To begin with, let’s try this little exercise in giving directions.

You need:

• Peanut Butter
• Jelly
• Bread
• Butter Knife

(Be prepared to make a mess and have fun.)

Communication isn’t just giving directions however. It’s also hearing what’s being said and following directions. How good are you at following directions?  (I know the first time I tried this experiment, I didn’t do nearly so well!)

Try this:

You Need: The instruction sheet (see below), one for each person in the group, and pencils for each person in the group.

This is a great activity and it really shows how hard it is to communicate with someone. It does a great job at pointing out assumptions and showing how careful and detailed you have to be with your instructions. It also shows that the listener has an important role to play. The listener must be very careful not to make assumptions and to be sure to take responsibility for what they are hearing by asking good questions.

One more thing this activity does is show how important definitions are to good communication. When I do this activity with my groups, I do it a few times and then take the time to point out some of the definitions the group has been using. For example, when they call one block the red square everyone knows which block that is. I also point out where a definition can come in handy.

For example “Stand the blue block on its side.” Well, which side? Long side, short side, fat side… how do you know? At this point, I take the time with the group to create definitions. “Okay, so when we say long side that always means this side of this block.” As you do this activity, you’ll see where assumptions are made and definitions can come in handy. In science, good definitions are vital. If somebody says, “I put the apparatus one meter from the ping pong ball.” Everyone in the world knows how far a meter is. There is a standard for meters, inches, cups, liters, ohms, joules and all sorts of measurements. Without good definitions no one would know what anyone was talking about!

Ready for MORE?

You’ll find several ultra-cool projects under the ‘Advanced‘ section that walk you step by step through not only the experiment but also the scientific method.

Rocketry
Fruit Batteries
Linear Accelerator
Measuring the Speed of Light
Alternative Energy
Hovercraft
Underwater ROV Robot
Crystal Radio

I’ve shown you how to take an ordinary experiment and transform it into something you can turn into a science fair… but you don’t need to enter a competition to work through these projects at all. Simply watch the videos and learn how to apply the scientific method to any experiment.