Designing and Constructing Marshmallow Catapults to Deepen Understanding of Energy

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SWBAT: Follow to the design steps to construct a catapult that can launch a marshmallow at least 5 meters and within .5 meters to either side of the target.

Big Idea

Engineering makes science content relevant and fun! Marshmallow catapults launch students into the wonderful world of engineering solutions.

The Design Process and Identifying the Need

10 minutes

Massachusetts utilizes an 8 step design process to guide students through the process of designing items that solve engineering challenges.  In this lesson, students will focus on steps 1-3 (Identifying the need or problem, researching the problem and designing possible solutions).


Marshmallow Catapult Design Challenge Description


Each group will design and build a marshmallow catapult using the following materials to achieve the goal:


1 meter of masking tape

2 Plastic cups

4 Rubber bands

2 Plastic spoons

2 Paperclips

15 cm x 15 cm Piece of cardboard

Large (standard size) marshmallows to launch

Goal: Launch a marshmallow at least 5 meters (in the air) and not outside of a ½ meter width of the target.

Day 1: Assign activity and partners, discuss rubric, answer questions and allow students time to brainstorm a solution with their partner.  Students should individually design a solution and then share their design.

Day 2:
Students should design a final solution and create orthographic projections of their design  HW: Draw their catapult as a technological system.

Day 3:
Students will be given the materials above and will construct their catapults, leave about 5-10 minutes for clean-up and wrap-up.  Students should be recording their updates and redesigns in their journal (a few pieces of paper where they will identify constraints, trade-offs, modifications, etc.).

Day 4:
Final construction and test!

Tips for test day: 

Have students move the desks to the side of the room facing inward.  Designate a launch area and measure out a 5-meter line and a half a meter wide span.  This designates the acceptable landing area.

Everyone should wear safety goggles!  There will be flying marshmallows and rubberbands might come loose or snap--state these dangers to your students. 

Have the rubrics laid out with a pen ready to record the grades.  Remember: you'll be judging the quality of the construction before launching.  This will allow you to discard the catapults after the launch occurs.  

Don't forget to purchase marshmallows.  If you do forget, a piece of paper rolled into a ball will work.

Researching the Problem

25 minutes

After students understand the problem, they are asked to research the problem--in this case catapult construction.  While researching the problem, I ultimately want students to find patterns in various catapult designs and then research the purpose of the commonalities, such as long arms, etc.  

Students used this worksheet to help guide their research.  If you choose not to use this, students may not get the information required to construct sound catapults, so that is discouraged.  

It is one thing to have students research catapults, but there is so much potential to tap into the Crosscutting Concepts, especially Structure and Function and Patterns.  As students began discussing the Structures and Functions of the catapults that they discovered, they realized that there is an arm, elastic materials that are stretched to store energy and that they were solidly constructed.



Developing Possible Solutions

20 minutes

Now that students have a sense of what it takes to make an effective catapult, they will take the remaining time to develop possible solutions with their partner.  I present the list of materials that students will have access to prior to letting them design solutions.  In addition, I explain that students will have 2 days to design, test and redesign a final version of the catapult that will be tested on day 3.

Students then use their research and Crosscutting Concept analysis to design at least 3 possible solutions, using available materials.  

Students create sketches and finish them for homework, if needed.

Tomorrow students will finalize one design that will be turned into an orthographic projection on day 2.