Building a Pumpkin Racer

In Science Club, our first task for "Things That Roll" is to build a pumpkin racer! I'll keep up to date on my notes here. The race is Sat Oct 28 at 2 pm.

The Great Carbondale Pumpkin Race

Official Rules

Building Instructions (PDF)

Thu Sep 28

review gravity, air resistance, friction, "spinning force," and inertia

address questions about antimatter (which is a real thing) and antigravity (which is a sci-fi thing)

share the results of a recent experiment about whether antimatter is subject to gravity just as matter is

Nothing’s the Matter With Antimatter, New Experiment Confirms
The New York Times - Sep 27, 2023

overview of Simple Machines, focus on lever and pulley experiments

Thu Oct 5

review of Simple Machines, focus on wheel & axle experiments

special guest Justin Harrell

Thu Oct 12

review Justin's suggestions for designing a successful pumpkin racer

focus on the challenge of parallel axles

break children into three groups, brainstorm all the ways your group can think of to 1) punch holes in the pumpkin and 2) make sure the axles will be perfectly parallel, come back together and share ideas, break into three teams based on people who have similar ideas, give children the supplies they request, build prototypes and test them!


whoops! not quite parallel



I had three sets of wheels on hand for the children to use in their experiments. One was from the storage bag of a pop up canopy tent, and the other two sets we removed from a pair of roller blades. The storage bag wheels came with axles. The roller blade wheels turned out to be just the right size for us to use knitting needles as axles!


the bamboo dowels we use to make knitting needles


Team 1

supplies - whole pumpkin, bamboo dowels, roller blade wheels

results - pumpkin racer turned to the left


Team 2

supplies - whole pumpkin, wheels from pop up canopy tent, clay

results - pumpkin racer turned to the right


Team 3

supplies - hollowed out pumpkin, size 10 knitting needles, clay

results - pumpkin went straight and crossed the finish line!

note: Team 3 had the smallest and lightest pumpkin of the group


This was such a joy to watch! They all had different strategies.

Team 1 used wooden blocks as a height measurement to try to put the dowels through the sides of their pumpkin evenly. They also used a spirit level. This team drilled their holes with a brace and bit.





Team 2 used the holes in the now wheel-less roller blades as a jig to ensure perfect spacing. They marked the locations of each hole with a pencil. This team made their holes with a spike and a rubber mallet.





Team 3 first hollowed out their little pumpkin. They then laid the knitting needles across the pumpkin opening and approximated where they would need to punch through. They punched new holes if needed when they felt the axles were not parallel. One side of the axle stayed in place because of the head of the knitting needle, and they put plasticine clay on the end with the point.

Thu Oct 19

second round of pumpkin racer prototypes

Thu Oct 26

building and decorating our final designs!

We ended up with three teams:
Low Tech Mini
High Tech Mini
High Tech Mighty

Thank you to Destinee, Francine, and Megan for the donation of supplies, and to Destinee, Kierstin, and Justin for the hands-on help! I also really appreciated the loan from Marcia of the special jig to help make parallel axles.

We are submitting two mini pumpkins: one low tech with knitting needle axles, roller blade wheels, clay, and duct tape (to fix a crack) and one high tech (using all thread, washers, locknuts, etc.). And we are also submitting one very big pumpkin with all thread axles and all of the hardware that is traditionally used in building one of these.

My personal favorite is the Low Tech Mini! I really wanted to honor the low tech idea that did so well in our trial runs, and there's no reason why all the racers need to be built just like the YouTube videos and online step-by-step tutorials say. It is Science, after all.

We are really excited for Saturday's race at 2 pm!

Fri Oct 27

Two teams ran late on Thursday night and also had to meet today for two hour bonus sessions because they needed additional time.

The Low Tech team built their design AND painted it in the 2 hours of Science Club, but both High Tech teams needed A LOT more time.

Sat Oct 28

2023 Pumpkin Race Photos!

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