Variables Unit

Investigation 1: Swingers

Today we are starting a series of activities that will help us understand how to design and conduct scientific experiments. Just like scientist, you will need a place to record your observation, experimental designs, and discoveries. Your journal and your wiki page will serve this function.

In your team, construct your swinger. Follow the instructions on your “How to Build a Swinger” sheet.

Propose An Experiment How many times do you think your swinger will swing in 15 seconds? How can you find out?

I will be the timer and you will be the counters. I will say Go and you will count silently---TO YOURSELF- until I say Stop

Variable What could you change in your swinger system that might change the number of swings in 15 seconds? Anything that you can change in an experiment that might affect the outcome is called a variable.

Part 1 Wrap Up Vocabulary Pendulum Cycle Variable Content/Inquiry What is a variable? What is a pendulum and where have you seen one? What variables might affect the number of cycles the pendulum makes in 15 seconds?

Part 2: Testing Variables

Lets Review What is a variable? Recall the three variables that we thought might affect the number of swings of a pendulum in 15 seconds. Mass, length, and starting position.

Standard Pendulum System Recall the setup of the pendulum you explored in Part 1. 38cm long, one penny, released straight out to the side, swing for 15 seconds. This can be referred to as the standard pendulum system.

What is an experiment?

An experiment is an investigation designed to find out how variables affect outcome. An experiment in which one variable is changed and the outcome is compared to a standard is a controlled experiment.

Test the variable of release position. How do you think this new release position will affect the number of swings? More swings? Fewer swings? Same number?

Test the Variable of Mass How can you find out if changing the mass of the penny will change the number of swings in 15 seconds? I’m going to show you how to add another penny to the paper clip. How do you think adding mass to the pendulum bob will affect the number of swings? More swings? Fewer swings? Same number?

Here is what we are going to do! We will make new swingers of different lengths to find out if length affects the number of swings in 15 seconds. But before we do, I’d like to record the number of swings our standard swinger made in 15 seconds for reference.

Relationship from Data Is there a relationship between the length of the pendulum and the number of swings a pendulum makes in 15 seconds?

As the length of the string increases, the number of swings _________. As the length of the string decreases, the number of swings __________.