Fun with STEM: The Catapult Project
Lesson Objective: Determine which variables affect the accuracy of catapults
Grades 6-8 / Science / Probability

Thought starters

  1. How does this lesson provide students with authentic opportunities to apply science and math concepts?
  2. What is the effect of focusing on controllable variables?
  3. How would this lesson have been different if students had not built their own catapults?
32 Comments
catapolt prject. i thout that you can relly change waht you have and get it were you {want] the bullet were you want. if you make changes.
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How may I purchase the worksheets that the students were using in the catapult video?
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I am wondering the same thing. This is a great project.
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Hi everyone, We emailed Zara to request copies of the worksheets she used in her lesson. Once we hear back from her, we will post the handouts under the "Supporting Materials" section. In the meantime, thanks for your patience!
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Look forward to the new supporting materials! That will be very helpful.
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Transcripts

  • STEM LESSON IDEAS
    THE CATAPULT PROJECT

    VO
    00:02:01 This teaching moment is made possible by Chase.
    00:02:08 [Stem Lesson Ideas]
    VERA ACOSTA
    00:02:21 My

    STEM LESSON IDEAS
    THE CATAPULT PROJECT

    VO
    00:02:01 This teaching moment is made possible by Chase.
    00:02:08 [Stem Lesson Ideas]
    VERA ACOSTA
    00:02:21 My name is Vera Acosta. I teach seventh grade integrated science and math at the Institute of Collaborative Education in New York. We’re using the fourth quarter this year to study what we call the catapult project.

    00:02:34 The catapult project is a six week project where we brainstorm a catapult, build a catapult, collect data, make improvements and then have a final set of data that we then analyze.

    00:02:46 We’re working on the integration of engineering, as well as looking at simple machines. We study the input output forces, projectile motion, speed. Then the integration for math includes probability – the probability of landing on the target.

    00:03:00 The main question that drives this project is what variables affect the accuracy of my catapult.
    00:03:10 [The Catapult Project]
    VERA ACOSTA
    00:03:11 The focus of today’s lesson was collecting data and then beginning their data analysis. So, determining their experimental probability for the data and beginning to consider which variables they might like to change.
    VERA ACOSTA [sync]
    00:03:23 You guys have been working with the catapults. You’ve built them. We’ve been working for about two weeks. We’re going to collect more data today. And we’re also starting to think about things that you can control with your catapults. Right? Things that you can change for better accuracy. Right?
    VERA ACOSTA
    00:03:44 I begin this lesson with a smath starter, as I call it, which is a question about which variables affect their catapult.
    VERA ACOSTA [sync]
    00:03:50 Would somebody like to share out some of the variables that they were thinking about?
    DELIA [sync]
    00:03:57 The angle of launch. Because the- the way we did it with our catapult, the angle of launch was kind of high. So, the projectile was flying really high up into the sky, rather than straight forward. So, I think that if we change the launch angle, it would be easier to predict where it went.
    VERA ACOSTA [sync]
    00:04:17 So, Delia’s path was like really high up. Right? She’s saying if she kind of lowers it, right, you can get more, like, the distance rather than the up and down. Cool. Nice. Alright. Let’s see. Let’s have Ansel.
    ANSEL [sync]
    00:04:37 Like, rubber bands. How many rubber bands you have. If you have a lot, the resistance is more, so you can have more speed of launch. And yeah, I guess that’s it.
    VERA ACOSTA [sync]
    00:04:49 What about the speed makes for accuracy?
    ANSEL [sync]
    00:04:53 Because if you want a target that’s far away, you’ll want more speed to launch it. If it’s closer, you want less speed to launch it.
    VERA ACOSTA [sync]
    00:05:02 And I would say getting it the same speed every time is also important. So, you’re cranking it back to the same place every time, too, right?
    VERA ACOSTA
    00:05:12 We brainstorm the same list of variables, in fact, when we began the project. So, kind of over and over, even though it might seem like I’m repeating the question, the students are in a different mind frame at each step of the journey.
    GIRL IN NY SHIRT [sync]
    00:05:25 So, length of the lever is a big part of it because the longer the lever is, the farther the projectile will travel, usually. Because, specifically, in ones from the last year that we looked into, the ones with shorter levers couldn’t travel as far because there wasn’t enough transfer of energy.
    VERA ACOSTA
    00:05:42 It’s important to ask the question at this stage because after that discussion is fresh in their mind, they go ahead and they launch their catapults. And in terms of control variables, it may be that they observe something new about a variable that they hadn’t observed before.
    VERA ACOSTA [sync]
    00:05:58 You want to be looking at your catapults to see why am I not getting perfect accuracy at the target. Is it some- is it something, like, with my actions or is it something with the design of my catapult. Alright?

    00:06:13 You are going to need your notebook, something to write with and we’re going to grab your catapults. Okay? That’s all you need.
    VERA ACOSTA
    00:06:29 When I organize the catapult trials, it’s important to have the students not crammed too close together to one another, just because they get in the way of one another. In our case, since it was kind of like a long corridor I had about half the students on one end, launching towards the center.

    00:06:45 As well as students kind of reflected over to the other side. We had three large bulls-eyes set in the center of the area. And then students would then decide where they would want to place their catapults, such that it was aiming for the center of the target.

    00:07:01 I have the students measure the distance between the catapult and their target in order to have a clear set of data with the least amount of variables and error.
    BOY [sync]
    00:07:10 We’re trying to measure the accuracy so we have to get a lot of data points of how far it went and what ring it hit on the target to measure the probability that it will hit the bulls-eye or any other ring.
    VERA ACOSTA
    00:07:26 Each student was required in their notebook to design their own data table, which I signed off on. And the question was how often is the projectile landing in the center, the first ring, and the second ring and, as well as, not landing on the target.
    BOY [sync]
    00:07:41 It hit the bulls-eye once and it hit the outside ring three times. But it hit the middle section five times.
    VERA ACOSTA
    00:07:50 They’re firing small crayon pieces. We discussed unfortunately the small inconsistencies where we’re not measuring the mass of each one. So, there is a small variable involved with that, but I find it to be a safe thing to launch across the classroom.

    00:08:08 Because there is a time restraint, I was hoping for at least 20 data points. There were some students in the class today who set the standards higher for themselves and were aiming for more 30, 35. And in fact, today, we had a student who had in total 75 data points in just three periods of work.
    GIRL
    00:08:28 I’m aiming for the target that’s in the middle, kind of, with the blue outer ring and the red in the side. And it usually hits in general. It misses a couple times and usually it goes farther than the target, so I’m trying to work on using less tension, versus more tension to shoot it.
    VERA ACOSTA
    00:08:49 There’s actually a lot of value in students just observing how a catapult launches. And even though we don’t have tools to measure the numeric value of the input and output forces, they can draw very strong conceptual conclusions about what’s going on when they watch it.
    JUDE [sync]
    00:09:08 I marked places where the rubber band could be [unintell]. Then, pulling it off. It just- it’s a more precise way of, like, knowing exactly where your [unintell] hit and having it the same every time.
    GIRL [sync]
    00:09:16 Like- Yeah, like, so how far you pull it back-
    VERA ACOSTA [sync]
    The accuracy.
    GIRL [sync]
    00:09:20 Yeah. That- that’s helping with the accuracy.
    VERA ACOSTA [sync]
    Wait, wait, wait. So, what’s the difference between, like, you’re saying this is the notch that you like, but what’s the difference between this and that notch?
    GIRL [sync]
    00:09:31 This actually changes, like, the- the size of the- the lever arm. Because it changes the- like, well it changes how much you move it, like-
    VERA ACOSTA [sync]
    00:09:44 How much you’re cranking it.
    GIRL [sync]
    Yeah. How much you crank it back.
    VERA ACOSTA
    00:09:47 What I found is that the students have complete ownership over their catapults. They’re really proud. They know that they’ve spent days and days and days, almost two weeks working on just to build something that’s functioning.

    00:10:03 They’ve had a lot of struggles just to kind of put the pieces of wood together, so they really own it and they’re proud. I think then, anything related to it – launching it and collecting data – they’re very much committed to any of the tasks that they are asked to complete.

    00:10:19 If we used a purchased set of catapults, I think it would be a completely different feel for the students. I think they wouldn’t be that interested. Or they would be- they would act more foolishly around it. Students are quite mature, considering that a catapult’s a little bit dangerous, right.
    VERA ACOSTA [sync]
    00:10:44 Alright, put your catapults away. Put your catapults away.

    00:10:49 There is a new science starter on the board. Can I have somebody read it out loud, please? Jude?
    JUDE [sync]
    00:10:56 How will we use probability with our catapult? Determine the experimental probability from your catapult data. Is it what you expected?
    VERA ACOSTA
    00:11:03 The next stage in the process after the data collection is to look at the data and tally how many times they’ve hit the target so that they can calculate their experimental probability.
    VERA ACOSTA [sync]
    00:11:14 We did a huge probability packet last week, but we know to determine the experimental probability for our case it’s the number of times it landed on the target over the total number of launches.

    00:11:32 Yeah, Brian?
    BRIAN [sync]
    00:11:33 We only got to fire it once because we had a lot of problems downstairs. So, wouldn’t our probability be 100 percent, either way?
    VERA ACOSTA [sync]
    00:11:43 Alright, yes. So, for people who did not get enough data, I would like you to team up with somebody else at your table who did. Alright?
    VERA ACOSTA
    00:11:53 I think the advantage of an integrated math and science course is students don’t shy away from the math quite as much. Oftentimes, they dislike the abstractness of it and in this case, every single science inquiry that we do in this course has a matching math component.

    00:12:14 So, students are really seeing the real math applied.
    VERA ACOSTA [sync]
    00:12:17 So, I noticed that the young ladies at this table, they got an experimental probability. Could you tell me what it was exactly you got it for?
    GIRL WITH BRAID [sync]
    00:12:27 Yeah. We didn’t have any- any times where it actually hit the center except for once. We decided to do it from the- the- the- yeah, the second ring and [unintell]
    VERA ACOSTA [sync]
    00:12:40 Okay, so specifically the number of times it hit the second ring.
    GIRL WITH BRAID [sync]
    Yeah.
    VERA ACOSTA [sync]
    00:12:45 Okay. So, number of hits on second ring.
    GIRL WITH BRAID [sync]
    00:12:52 And so, we had seven out of 18.
    VERA ACOSTA
    Alright, so you had seven out of 18.
    GIRL WITH BRAID [sync]
    00:13:03 And then, so we turned that into a decimal by dividing seven by 18 and got point-three-nine. And then we turned that into a percent, which was 39 percent.
    VERA ACOSTA [sync]
    00:13:16 Nice. So, we can make a sentence, right? You- you have 39 percent accuracy on your second ring.
    GIRL WITH BRAID [sync]
    Yeah.
    VERA ACOSTA [sync]
    Nice.
    VERA ACOSTA
    00:13:26 I provide my students with a worksheet to help scaffold how they’re going to solve their experimental probability. It asks them to in one location write down how many times their crayon landed on each section. And then gives them another box right next to it to determine what the experimental probability is.
    GIRL WITH BRAID [sync]
    00:13:48 So, experimental probability- So, one out of 18 and then two out of 18, seven out of 18.
    VERA ACOSTA
    00:13:59 The next step is to identify which variable they’d like to change in their catapult, write down what it is and then draw a sketch on how they’d like to make that change.
    BOY IN BLUE SHIRT [sync]
    00:14:11 We’re going to put supports on the side of the structure to keep the lever from wobbling back and forth.
    VERA ACOSTA [sync]
    00:14:17 Alright.
    BOY IN BLUE SHIRT [sync]
    Does that sound okay?
    VERA ACOSTA [sync]
    That sounds good. And are you still going to try and use the weight at the bottom?
    BOY IN BLUE SHIRT [sync]
    Yeah.
    VERA ACOSTA
    00:14:23 At the end of the catapult project, the goal is for the student to be able to identify which variables did, in fact, influence their accuracy. And what they did to contribute to the improvement of accuracy.
    ANSEL
    00:14:37 Our rubber band wasn’t strong enough to shoot it far enough to the target, so we thought about putting another rubber band so it had more resistance against when we pull it back, so then it’ll go farther and hit the target.
    VERA ACOSTA
    00:14:51 The STEM framework asks students to think like scientists and the students in my classroom are not only thinking like a scientist, but then performing tasks like a scientist. Making observations, making predictions, observing variables, making conclusions about how that variable influences something else and how they’d like to control it.

    00:15:15 It’s very much a problem solving project. And for me, really seeing the students be so invested and enthusiastic and- and wanting to push themselves to make great things – it really is a success story for every child.
    VO
    00:15:39 This teaching moment is made possible by Chase.

School Details

Institute For Collaborative Education
345 East 15th Street
New York NY 10003
Population: 480

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