Grade 3 Vehicle Challenge

Here are some photos from our grade 3 open ended challenge to design a WeDo vehicle.  I reviewed 3 ways to connect motor to wheels before they started: gears, pulleys, or direct drives. Students used the base WeDo kit. However, I added additional long axles and tires/wheel from the WeDo Resource kit.

Grade3 Vehicles 1

Students were trying first to make a stable chassis out of rubber bands.

Gifted Builder

This student and his partner quickly came up with a functional car design. He does many building projects at home with his father. He quickly built a chassis and drive train.

Grade3 Vehicles 3

Notice the double belt

Grade3 Vehicles 4

These students built the drive train (out of gears first) before building the chassis.

Grade3 Vehicles 5

This was the final car from the student who is a gifted builder. They hid the engine under some LEGO plates and added a realistic steering wheel.

Grade3 Vehicles 6

These students decided the more belts, the better. However, I believe they will be in opposition to each other and one will have to be removed.

Grade3 Vehicles 7

Here’s another gear design. Usually, belts designs are easier than gear designs. However, 2 teams came up with good gear designs.


One girl did some design drawings, which is unusual without it being required.  I suggested it but did not require it.



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5 Responses to Grade 3 Vehicle Challenge

  1. Actually, I was wrong about the “dueling belts”. They do go the same direction.

  2. Jason Hubbard says:

    Love your site and posts! Thanks for doing all this. Questions…do you have design constraints for this lesson? How much pre-teaching of frame/chassis/wheel and axle, etc. do you do? About how many sessions/how long do the students get? Sorry for so many questions! I currently have my 3rd graders building and programing the 20 basic Getting STarted WeDo models , then I want to spring into a design challenge in which they could use what they learned and this sounds perfect!

    • JohnHeffernan says:

      Thanks, Jason. Good questions. The complete lesson (and lessons for a PK to grade 6 robotics curriculum) is in my book, by the way. You can look on or click on Book above to get a copy. I do talk about chassis a little and definitely review the 3 ways to make the wheels turn (direct coupling, gears, or belts and pulleys). I find 3 graders can make a car in 1-2 50 minute blocks. One thing you might want to consider is going one of the LEGO models first, we do Dancing Birds in grade 1, Drumming Monkey and Spinning Top in grade 2 (along with an amusement park ride open ended challenge), and Amazing Adventure Airplane Ride before the car in grade 3.

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