Experimental Design

How to build a better paper airplane

A lesson on experimental design and an engineering design process.

SuperSoaker Inventor video: https://www.youtube.com/watch?v=SYq6aKLuSk0

Open Ended

Have you ever wanted to invent or create something? If so what? It doesn't have to be technical or a new product (like on Shark Tank); could be a new recipe, song, poem, video game, book,...

Who can make the "best" paper airplane?

Construct a paper airplane and throw it. How can we decide whose plane is the "best?" This will be your "control" plane.

Open Ended

Define "best." What criteria can we use to determine the "best" paper airplane?

"Best" paper airplane could be the plane that

• flies the furthest distance

• flies the straightest

• is in the air the longest

• is the most aesthetically-pleasing

1. ASK. Define the problem and constraints

Problem: Construct a paper airplane that flies the furthest (greatest distance).

Constraints: Time and money (resources).

2. Imagine

Brainstorm ideas and choose the one you want to test

Open Ended

List at least three modifications that could be made to your basic "control" airplane to make it fly better. Hint: In the classroom I would have the following materials available: different kinds of paper; scissors, tape, paper clips.

3. Plan

• Identify independent and dependent variables

• Identify factors that should be kept constant (the same)

• Write hypothesis

• Write procedure, create a data table, gather materials

Variables vary (change); Constants stay the same!

IV-I decide before the experiment; DV-measured during/after experiment.

HYPOTHESIS

An informed prediction ("educated guess) about the outcome of an experiment.

General format: If...then...because...

If (write about a change in the i.v.), then (write about a predicted change in the d.v.), because (write why you think the predicted change will occur)

Multiple Choice

RESEARCH QUESTION: How does the number of paper clips placed on the bottom of a paper airplane affect its flight distance?

The _______is the independent variable while ________is the dependent variable.

• flight distance; number of paper clips

• paper clip position; flight distance

• throwing force; flight distance

• number of paper clips; flight distance

• flight distance; size of paper

Open Ended

RESEARCH QUESTION: How does the number of paper clips placed on the bottom of a paper airplane affect its flight distance?

List factors that should be kept constant. (What else besides the i.v. do you think might affect the d.v?)

Open Ended

Write a hypothesis for the RESEARCH QUESTION: How does the number of paper clips placed on the bottom of a paper airplane affect its flight distance?

Remember: If...(write about a change in the i.v.)...then...(write about a predicted change in d.v)...because...(write why you think the change will occur)...

Multiple Choice

Three students throw their planes. Based on the following data, who's plane is the best? Distance flown is listed with a standard unit of measure- (lengths of a Butterfinger candy bar)

• Joe (17.25 b.f.'s)

• Moe (14 b.f.'s)

• Little Joe (15.5 b.f's)

• cannot be determined

Open Ended

Explain why one throw may not accurately represent how well the plane flies.

Why you shouldn't do just one trial in an experiment.

• Planes fly differently each time

• Variability in measurements

• Solution: Do it again...and again... (Repeated trials)

• In school we will try to do at least three trials and use a median or mean (average) to represent the data

Notice where the i.v. and d.v. are located. What is your conclusion? How does cost factor into your conclusion?

Open Ended

Usually, it is best to make a change to just one independent variable at a time and keep everything else constant. Explain why this is a wise idea. (HINT: THINK--Imagine if in our experiment we added paper clips to the bottom of the (control) plane AND changed the design (way it was folded) and the plane flies a lot farther? What would your conclusion be?)

Why should you change only one variable at a time and keep everything else constant?

• So that you can be confident that any change in the dependent variable is due to changes in the independent variable and not any other factor.

• Can save time and money-see bird feed example at left and "my lights don't work" story.

The cycle never ends! (until you run out of time or money!)

Check your understanding of experimental design concepts.

Do the questions on the following slides. Be sure you understand why the incorrect choices are wrong and why the correct answers are right!

You may review this slideshow afterwards for practice.

Multiple Choice

What is a factor that is measured for change in an experiment and may respond to changes in the independent variable?

• control

• constant

• independent variable

• dependent variable

Multiple Choice

What is the factor that the scientist changes on purpose?

• Dependent Variable

• Independent Variable

• Constant

• Control

Multiple Choice

What are all the things that are kept the same in an experiment?

• Constants

• data

• dependent variables

• independent variables

Multiple Choice

Maria designed an experiment to determine how the amount of sleep affected grades on a physics test. Which of the following is the best written hypothesis?

• If students get higher grades on the test, then they will get more sleep.

• If students get more hours of sleep, then they will get higher grades on the test because they will remember what they learned better.

• If students get higher grades on their test then they will get more sleep because they will more rested for their test.

• If students get a small number of hours of sleep, then they will get lower grades on the test.

Multiple Choice

Dory set up an experiment to see how the mass of a ball affects the distance it rolls off a ramp. Which of the following is a valid hypothesis?

• If the ball has a larger mass, I predict it will roll farther, because it has more inertia.

• If the ball has a larger mass, I predict it will not roll as far, because it has more inertia.

• If the ball has a smaller mass, I predict it will not roll as far because it will be affected by air resistance more.

• All of the above are valid hypotheses

Multiple Choice

Students used various temperatures of water to see which one dissolved candy faster. All of the following should be kept constant except for

• Amount of Candy

• Amount of Water

• Temperature of Water

• kind of candy

Multiple Choice

Steve wanted to see if the type of fertilizer made sunflowers grow larger. What is the dependent variable?

• Type of fertilizer

• Size of sunflower

• Type of sun flower

• Amount of sunlight

Multiple Choice

Dory set up an experiment to see how the mass of a ball affects the distance it rolls off a ramp. What is the dependent variable?

• distance traveled by the ball

• height of the ramp

• mass of the ball

• ball type

Multiple Choice

If you were testing how well different dish soaps cleaned grease, the independent variable would be the:

• dish type

• amount of grease

• dish soap type

• grease type

Multiple Choice

Students used various temperatures of water to see which one dissolved candy faster.

What was the Independent Variable?

• Amount of Candy

• Amount of Water

• Temperature of Water

• Time for Candy to Dissolve