Practice for the test

Below are two practice questions. As you're reading, look for errors with the scientific method. There are bulleted questions below the story. Answers follow the questions. (Don't look at the answers until you try!)

I play volleyball at my school using a Mikasa ball. Other ball brands are Mizuno, Spalding, and Tachikara.  I will stand from behind the serving line, in the right back. Melissa will serve the Mizuno ball, Lucy will serve the Spalding ball, Quincy will serve the Tachikara ball, and Vanessa will serve the Mikasa ball. We will see who serves the best.

• What is the question?
• What is the hypothesis?
• What is the IV?
• Name two errors in this experiment.
• Why is this an error?
• How could you fix it?

I want to get soccer cleats that give me the best trap (stop) when a ball is kicked to me. I go to the store and buy Adidas, Nike, and Umbro soccer cleats for me and two of my friends. I will also buy three identical new soccer balls to use. Sydney will test the Adidas. Caroline will test the Nikes. Alexa will test the Umbro. Whoever can kick the furthest will be what I buy.

• What is the question?
• What is the hypothesis?
• What is the IV?
• Name two errors in this experiment.
• Why is this an error?
• How could you fix it?

Answers:

With which ball can I serve the best?        **Do you see a problem here? 
If I serve with the [fill in the blank with a brand name] ball, then I will serve the best.
IV: brand of volleyball (Mikasa, Spalding, Tachikara)
Error #1: "the best" is not a specific enough direction. She should have said, "We will see with which ball I can serve the deepest into the back court."

Error #2: too many IVs - The only IV should be the ball brand, but by having different girls serve the different balls, the person serving is now a variable. The person serving should be constant.

Which soccer cleat brand give me the best trap?

If I buy Nikes, then I will be able to trap the ball the best.

IV: brand of soccer cleat (Nike, Adidas, Umbro)

Error #1: She wants to buy the cleats that have the best trap, but she's saying she'll buy the ones she can kick the furthest are the ones she'll buy. She can't test for two things. Choose one.

Error #2: Too many people kicking balls. Since there are different people, you have too many IVs. There can only be one IV. Choose one person to do the kicking in each of the different soccer cleats.