Engineering Project: Balloon Car

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SWBAT work through the engineering design process to plan, build, and test a car powered by a balloon.

Big Idea

Students act just as real scientists do, to create and test a vehicle they have designed, that is powered by only a balloon.

Rationale and Preparation

The Why Behind Teaching This: 

The engineering design process is a process used by scientists in the real world.  This process encourages scientific thinking and promotes team work.  This lesson is directly linked to standard 3-5-ETS1-1: Define a simple design problem reflecting a need or want that includes specific criteria for success and constraints on materials, time, or cost.   I provide information regarding the project objective which includes limitations that the group must consider while designing and building.  While researching and planning, students will see a variety of designs on various websites and group members may have different ideas that need to be considered.  By working through this process, the activity also covers standard 3-5-ETS1-2: Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem.

Reading standards are connected to this lesson as well through the research process. Standard RI.5.7: Draw on information from multiple print or digital sources, demonstrating the ability to locate an answer to a question quickly or to solve a problem efficiently, is covered through this activity.  Students will be finding models created by other people and considering those models when designing theirs.  They will use the internet for this research and will view a variety of sources during the process.  Math is also connected through measurements made requiring them to apply math practice MP.5: use appropriate tools strategically and MP.6: being precise.  

Additional Lesson Information: 

This lesson takes approximately 2 hours to complete. I do my engineering projects on our school's half day professional development days because I have 2 hours of instructional time with the students.  If you choose to do this activity on a normal school day, it will probably take two days.  Day one would be the planning and design day.  Day two would be the building and testing day.  

Lesson Goal: 

The goal of today's lesson is to promote scientific thinking through the use of the engineering design process.

Success Criteria: 

Students will demonstrate their understanding of the process by completing each step of the process: research, plan, build, and test, to create a car that will travel the greatest distance, that is powered only by air released from a balloon.  

Preparing for Lesson:

Warm Up:

Guided Practice: 


  • Enough Straws for each group to have at least 1
  • Enough rubber bands for each group to have 1
  • Masking tape  
  • A variety of other materials for groups to choose from such as bottles, small boxes, CDs, bottle caps. etc. 

Wrap Up: 

  •  Measuring tape and wide open space for testing 

Warm Up

5 minutes

I begin today's lesson by showing the following video: 

The question at the end of the video asks "How would you change the design of the car to make the car go further?"  I explain to the class that our engineering project for today will be to improve the design of that car, using all recycled materials.  

I display the Engineering Design Process template and review the steps with the class.  

Guided Practice

10 minutes

Selecting Groups: 

I have a can filled with 5 different colored tokens.  I walk around and ask students to all take a token.  As they are pulling out tokens, I am taking mental note of what color my high students get.  This can work in two ways to divide students.  If the high students are getting mostly the same colors, then I can have the class get into groups with one of each color in each group.  That will ensure that there is a high student in each group.  If the high students are mostly getting different colors, then I group the class based on color.  For example, all the greens together.  It works out that most of them got different colors so I form 5 groups of students who all got the same color.  

Engineering Project Task:  

After getting into their groups, I provide each group with a copy of the Engineering Design Project - balloon task sheet.  I review the objective, materials, limitations, and things that are allowed with them.  I also provide each group with a copy of the Engineering Project Planning Sheet.  Groups will have to complete this planning sheet during the research and planning steps of the process.  

Assembling the Straw and Balloon To Operate the Vehicle: 

I model how to assemble the balloon and straw together to power the car.  To do this, I place the balloon on the long end of the straw, not on the flexible bent end.  I use a rubber band to secure the balloon onto the straw and explain that when students do this, they do not want to secure it too tight or the rubber band will squeeze the straw closed and prevent air from getting into the balloon.  I then wrap tape around the rubber banded area to secure it even more. 


90 minutes

Working Through the Process to Create Their Structure: 

Research and Planning: 

Students spend the first 30 minutes of the time allotted on researching and planning.  The begin the process by getting a laptop and researching possible ways to build their structure.  Part of the planning sheet asks them to elaborate on what they learn from this research.  The majority of groups find various pictures of balloon cars and look up videos on Youtube that help them plan.  I want them to explain on the planning sheet how they chose their design from these various pictures and videos.  They must submit their planning sheet and drawing of their planned structure to me for approval prior to receiving their materials. 

Building, Testing, and Improving their Car: 

Once I have approved their plan, they get their materials and begin building. I circulate while groups build and observe their design.  I try to catch errors before they get too far into their construction so that I can help them come up with possible solutions.  

The first Video of students building was chosen because the group is building and there is a clear error in the design.  I quickly notice that their axles are not level, which means not all four wheels will touch the ground when they are attached.  I point this out after recording them working for awhile.  They had not even noticed the error until I pointed it out to them.  I gave them some suggestions on things that may help.  I told them they may want to weigh down the higher side of the car some how or add slightly larger wheels to the higher side so that they will touch the ground.  

Video 2 of students building was chosen because it also shows an error in design.  The students in this video are building their car by taping the axles on the bottom of their car that is going to be used as the body of the car.  I ask this group how axles work on a car.  The aren't really sure so I explain that they spin the wheels of the car.  The axles have to be able to spin in order for the car to move.  I ask them how their axles will spin when they are taped down to the box.  The girls realize they will need to adjust their design and begin by removing their axles from the box.  I give them some suggestions such as poke holes in the box to stick the axles through.   This same group is in a picture below and you can tell they completely changed everything about the design of their car due to this error.  Their final car has a completely different body as well as different wheels.  These are some pictures of groups with their final cars.   


As students begin finishing their cars, they begin testing and trying to figure out ways to improve their designs.  Most of the cars are not successful at first and students are frantically coming to me to offer suggestions.  Some of the common errors I saw were that the balloons were heavy when blown up and were dragging on the ground thus holding the car back.  I discussed friction with the groups that were having this error and sent them to figure out a way to support the balloon so it did not drag the ground.  Another common error was that ground put their wheels too close to the body of the car and they were rubbing which stopped them from spinning.  I again used this time to discuss friction and suggest to them that they try it again after they move the wheels farther away from the body of the car.  

Wrap Up

15 minutes

Testing their Designs: 

After 90 minutes of building, I ask students to clean up and return to their seats.  I take the class out into the hallway to test the cars.  The hallway is a good location because there is a long open space in case any of the cars travel a long distance.   We test each car 3 times and we use the longest run as their distance.  Students are responsible for making their own measurements so that I can check for proper use of the measuring tape.  

Unfortunately not all groups had a car that was working.  Groups were good about trying various things to get their cars working, but some groups did get frustrated and when time was running out, they gave up trying things.  One group had a car that was moving, but they did not follow the guidelines outlined on the task sheet.  One guideline was that all cars had to have at least 2 wheels and their car had no wheels.  They argued that their car worked better without wheels because it was made out of a very small box and was so light that it slid across the floor with no wheels.  When they added it wheels, they weighed it down and it did not move.  I told them unfortunately, limitations and guidelines are something real scientists have to deal with and their car did not qualify.  I did let them test it, but it did not count in the competition.  

Video of Student testing winning car

We competed against the other fifth grade classes in this competition.  The winning car for our class traveled about 100 cm less then the overall fifth grade winning car.  My students observed that the car that won, designed their car in a way that the air released from the balloon very slowly.  We discussed how they must have come up with a way to limit the amount of air that escaped from the balloon.  We talked about some possibilities such as tightening the rubber band that is holding the balloon on the straw.  I told students if this is one project they want to improve, talking to the winning group and finding out what worked for them would be a good starting point.  Then they can make adjustments to their design based on that information.