"The Town of Left and the Town of Right are separated by a dotted yellow line, and no one on either side can remember how things got to be this way! One day, an unlucky citizen crosses the line--forcing the Order of the Ambidextrous Knights who guard the border to take action. Unfortunately, the only ammunition they have around is marshmallows--50,000 boxes worth! So begins the Marshmallow Incident, a tale of Left and Right, and Right and Wrong, with an incredibly silly but delicious dose of Mallo-Puffs and Marsh-Pillows thrown in. Kids will read it once and then beg for s'more!"


design challenge


How can we prepare to launch marshmallows in this town to the other side? 

Students should engage in a Driving Question Board to elicit ideas and ask questions about what they need to know to answer this question and solve the problem. 


​Simply Suggestions:

  • Plastic spoon

  • Metal spoon

  • Clothespin

  • Dixie cup

  • Rubber bands

  • Notecards

  • Popsicle sticks

  • Bottle caps



Encourage students to think about the user of the catapult. How will they make it easy enough to use? Who is their audience? How will they make it adjustable? Ergonomic? Is it transportable, and water proof? 


Students will begin to draw on background knowledge and experience to think about ways to approach the challenge and solve the problem. Allow class discussion of considerations and ideas. This stage may involve some exploration with materials and ensure understanding of the constraints. 

Your Choice: 

  • Freestanding (meaning it cannot be fixed to a surface

PE aligned

Including, but not limited to: 

  • Physical Science the depth of discussion and target of constraints will meet the standards. 


Working in teams, students draw a diagram of their solution. This should include indication of materials and labels on their design. If notebooking, all students should have the design in their notebook and be able to communicate their plan. This should be thorough enough that any other group could follow the plan.

Teacher Tip: If planning on whiteboards, give students different color markers to ensure all are contributing. 


Students must follow their initial plan using the materials they outlined. Hold them accountable for giving their first design a chance. This thought varies, some feel that they should be able to change it as they see flaws, but I tend to hold them to their first submitted plan. 

Teacher Tip: For materials management, you can assign students roles to get them all involved in building. 


1. Height - can they launch it over the predetermined "wall" (don't just encourage them to hit the ceiling) This is an easier test for them to feel success. 

2. Distance - how far can you launch the projectile, measure the length and record their data. 

3. Target - are they able to accurately control the distance and height. Consider having one set with a start line and a fixed target, or having students choose where to place it. 

Teacher Tip: I try not to limit their testing with this challenge because it's so quick and easy for them to launch. Set up the testing stations in separate parts of the room so that they can spread out. 


This step is critical to students persevering. Be sure to allow them to make tweaks and test again, or even revisit their plan. This is a reflective piece, and a great time to circle back to thinking about the user. 

additional texts

Wonderopolis - Why are some people left handed? 

Wonderopolis - Are you all right or left brained? 

Wonderopolis - What is a catapult? 

Britannica - Catapult history

Real World Physics - trebuchet