Jet Straw
Victoria Deneroff, PhD
I stole this idea many years ago from the NASA website, although I have adapted it to be an engineering challenge rather than a science activity. The original appears to no longer be easily available on the web.
Design Challenge
Build a jet straw air engine which produces the highest rotational speed.
What is a Jet Straw?
The jet straw is a simple engine that is powered by air released from a balloon. It is a system consisting of a balloon, bendable straw, rubber band, straight pin and pencil eraser. The straight pin is used as a pivot point around which the system rotates.
Beginning Ideas
In your journal write down what you think is the best way to construct a jet straw engine.
Stage 1: Messing Around and Asking Questions
Use the rubber band to attach the balloon to the straw so that it will rotate around a pivot point. Use your journal to record the different ways you tried to make the engine, and what you finally tried that worked. Brainstorm questions that will help you make a jet straw which rotates more quickly. Make a list of the questions, and in pairs decide on one to investigate.
Stage 2: Tests and Experiments
Decide how you are going to find the answer to your question by conducting an experiment. Each person should write down the step-by-step directions for conducting the experiment. The procedure must provide a way for you to collect quantitative data by taking measurements. What these measurements might be is up to your team. Consult with the teacher when you think you have a good procedure.
Stage 3: Observations and Measurements
Record your observations and measurements in your journal. As a class we will discuss your observations and what they mean.
Stage 4: Claims
What do you claim is the best way to design a jet straw engine, based on your tests? Write in your journal
Stage 5: Evidence
In your journal, explain how you know this is the best way.
Stage 6: Prepare a poster which explains
A. What your question is.
B. What your findings are.
C. The scientific explanation for your findings
D. What your recommendations are for others who want to build a jet straw engine.
E. We will discuss all the findings as a class.
Stage 7: Reflection
Reread your original questions. How have your original ideas changed, or grown? What do you wonder about now?
Stage 8: Redesign.
With your partner, revise your jet straw engine design, making a sketch of it in your journal. Build your revised design and record how it works.