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Picture of The Catapult Lab

Here are links to the lab and a general lesson plan. This lesson is designed for middle grades, but could be used as early as 5th grade or into H.S.

Pre Lab Reflection

Catapult Lab with Claim, Evidence, Reasoning

Lesson Objectives: Students will demonstrate the ability to build a siege weapon. Students will gather data using their catapult. Students will make a claim, use evidence, and reason with that evidence. Students will analyze Newton's Laws and describe how a catapult can relate to each law.

Warm Up: Discuss Newton's three laws of motion.

Class Activity: Watch the youtube video on how to build a popsicle stick catapult (without stopping the video).

Hand out all materials and allow students to build their own catapult using either the video again or using the images in the instructable below.

Allow students to test their catapults with either marbles or mini marshmallows.

Closure: How does the catapult relate to Newton's three laws of motion?

Extension Activity

Mod 1: Some students decide to tape an extra craft stick to the back "A" frame (horizontally) to influence the stopping point of the throwing arm for a higher trajectory.

Mod 2: Some students decide to tape two extra craft sticks to the back "A" frame (vertically) on either side of the throwing arm to prevent it from wiggling to the left or right.

Lab: What all teachers should be striving to get their students to master...

Claim, Evidence, Reasoning

My students take one class period to test their catapults in a catapult tournament. We push the lab tables together (end to end) to make a series of long tables. We set up three cups at the end of the table filled with sand. Students work in pairs to either hit the cups (one point) or sink the marble into the cups (3 points). First to 10 wins, but they have to win by 2. The team who shoots second at the start of the game gets the last shot.

Winners play winners, losers play losers.

After students have a chance to test their catapults, identify problems, and make adjustments they get to form their claim. Claim: To launch a catapult 300 cm, students must be aware of ___________________ and __________________.

They are allowed to fill in the variables (including distance, but that's the length of our lab tables pushed together).

Possible variables include but are not limited to:

  • the distance the throwing arm gets pulled back in cm.
  • the number of rubber bands
  • the mass of the projectile
  • the angle the throwing arm gets pulled back
  • the angle of the throwing arm at it's stopping point
  • the size of the basket

Evidence: Students then design an experiment to test their claim. They collect data and create a data table.

Reasoning with the collected evidence: Students are then expected to be able to use the evidence they collected to support their claim. For example: To launch a catapult 300 cm, students must be aware of the distance the throwing arm gets pulled back in centimeters and the number of rubber bands. First, our team used a metric ruler to mark centimeters 1-6 on the "A" frame of our catapult. Next, we collected 4 rubber bands. To keep the mass of the projectile the same, we used the same marble with a mass of 4.5 grams for the entire experiment. According to our data, using 3 rubber bands and pulling the throwing arm back a distance of 4 cm resulted in a throwing distance of 300 cm. Our next closest trial was using 2 rubber bands and pulling the throwing arm back 6 cm because the marble landed 315 cm away. One possible variable we weren't able to account for was...

Step 1: Popsicle Stick Catapult

Picture of Popsicle Stick Catapult

I teach 7th-grade science. During our physics unit, I have students build craft stick catapults to help demonstrate Newton's Laws of Motion. They also use their catapults to create a claim, develop an experiment to test their claim, and use evidence from the experiment in their reasoning. For more information about the catapult lab, you can skip to the last step. If you're no longer a student, don't let that stop you!

If you like this Instructable, please consider voting in the Tape Contest. Thanks! Now let's get building!

AnneR265 months ago
Can't reply direct - it says I have too many cookies or something! Yes a trebuchet has a counter weight at the base of the beam....but basically, so has this stick model. It is NOT a catapult, which is worked with a stretchy band from a Y shaped static hand held frame.
Biodynamic (author)  AnneR265 months ago
I appreciate you trying to convince me, but even your all caps "NOT" is NOT enough. Feel free to convince all of the other instructable authors who built "catapults" (that look and function just like this one), that they are not catapults. I'm also getting the too many cookies message and it's quite annoying.
Thanks for sharing this great resource! The lesson and student activities are really awesome and I bet the Catapult Tournament is super exciting. :)
Biodynamic (author)  WeTeachThemSTEM5 months ago
I just edited the link to the lab if you're interested. Thanks for looking!
AnneR265 months ago
This is not a catapult - it is a trebuchet...!
Biodynamic (author)  AnneR265 months ago
I thought a trebuchet used a counterweight to throw a projectile?
It would seem to be a catapult: “The sling is not what makes it a trebuchet instead of a catapult. Catapults get energy from tension (usually torsion) and the arm hits a stop near the top of its arc to release the projectile. Trebuchets get their energy from gravity.”
jessyratfink5 months ago
Awesome! Thanks for sharing your lesson plan too :D
Biodynamic (author)  jessyratfink5 months ago
No worries! It takes a village to raise a teacher.