We received mixed feedback from the different stakeholders. The students were most excited by the trebuchet and the DIY speaker due to the greater degree of iterability. Teachers responded most positively to the trebuchet due to how closely it aligned with the classroom curriculum. We followed up with the teachers by sending them a questionnaire for eliciting feedback, and one of our participants said:


However, our partner from Microsoft strongly advised us to pursue either the turbine or the speaker, because he feared that the trebuchet activity would descend into chaos and detract from the educational value.

All three of us were excited about the trebuchet as a design concept despite the pushback, and the feedback we received from the other stakeholders gave us the conviction to push on with the trebuchet as our candidate. At this stage, our design challenge shifted to that of stakeholder buy-in by making sure that the trebuchet activity is manageable in a classroom environment.

We created a Wizard of Oz prototype that simulated the experience of the activity. In this iteration, a fake accelerometer was attached to the arm of the trebuchet to "measure" the speed of the projectile. The experiment allowed the participants to change the position of the fulcrum along the "arm" and "base" of the trebuchet. The trebuchet this time was created from lasercut plywood for additional stability, and the digital worksheet was created using Figma. We also provided a paper worksheet to help record the data across trials.

What we learned

Our participants thoroughly enjoyed the activity, and the parents thought the experiment was both educational and fun.

• Adding and removing weights was time consuming but exciting
• The participants didn't find the digital visualization to be valuable
• The paper worksheet was redundant and ignored by all our participants

What we changed

For the next iteration of the prototype we would like to make the following changes,

• Change the weight holder to a bucket shaped design
• Provide visual assembly and operation instructions
• Digitize the tracking of trial data and variables and remove the paper worksheet

We got the opportunity to test our prototype with eighteen 4th graders at Kokanee Elementary. We provided students with construction kits made from laser-cut cardboard pieces designed for assembly in groups of 3. We wanted to see if the activity would be engaging and educational, or descend into chaos.

We observed the students in their natural state with bated breaths, and to our surprise there was no descent into chaos! Both teachers and students in the classroom really enjoyed the classroom project.


During the post-activity discussion, we conducted a quiz. The students demonstrated very clear understanding of the relationship between kinetic and stored energy. The overall experience was fantastic, and we received some very valuable insights.

• Students were able to assemble the trebuchet in much less time than we expected.
• The activity was a perfect fit for the 4th grade curriculum, as the students learned about stored & kinetic energy in class just 1 month prior.
• The pouch design was difficult to operate, resulting in frequent launch failures.

What we demonstrated so far has been really educational, but the construction was from laser-cut cardboard, and the experience is not very iterative.

• We decided to revert back to the cup design for launching projectiles due to operation difficulties.
• We need to include specific challenges and goals so the experimentation is more guided.
• The digital interface should allow the students to tweak and track the effect of different variables across trials.

The construction so far used laser-cut cardboard as the material. This material would be optimal due to its weight, stability, and cost for a commercialized kit. However, the typical elementary school classroom would not have access to a laser-cutter. Inspired by origami, we opted for a papercraft trebuchet body instead, one that could be constructed using card stock.