Skip to main content Skip to main content

Project Playbook: Educator Edition

Put Put Boat

Investigate thermodynamics and the heat engine.


Steam engines are external combustion engines that perform mechanical functions, using steam as their working fluid. The Put-Put boat is a an experiment in steam power. Using simple materials that are easily sourced, you can build a miniature steam boat that will propel itself around a body of water.

❏ Tin can
❏ Tape
❏ Bendy straws
❏ Candles
❏ Homemade toy boat


  1. Carefully, cut off the top and bottom of a tin can.
  2. Cut down the side of the can to open and flatten the aluminum. Use the creases made in the can during the machining process as a guide to cut along.
  3. Trim the edges of your can down, leaving a rectangle of tin about 8” wide.
  4. Fold the tin in half, widthwise, so you have a 4” folded section. Apply weight evenly on the fold using a flat object.
  5. Tape the open end of the folded can closed.
  6. Trim the height of the folded tin to 2 ½”. Keep the strips of tin for use later in the construction.
  7. Use a ruler or flat object to crease the tin and bend it, widthwise, a quarter inch on both sides. Carefully work these bent parts of tin all the way over so it is folded on itself. This is the heating element for the boiler.
  8. Use a pen to open up the end of the tin fold that has not been sealed.
  9. Cut the bendy straws 2” from the bendy part on the long part of straw.
  10. Put the cut end of the straws ⅛” into the boiler next to each.
  11. Seal the boiler using glue or an epoxy. Be sure you get all the folded and open airways sealed.
  12. Seal around the straws as well. You should now have a pocket of air with two straws protruding from the end.
  13. When the glue has dried, attach the boiler to the back of your boat.
  14. Cut ½” of birthday candle. These work well because they create a small flame.
  15. Attach the candle to the deck of the boat.
  16. Add a bit of water to the boiler by pouring through one of the straws until water comes out the other. This will provide moisture to make steam. While keeping a bit of water in the straws, lower them into the water.
  17. Attach the boiler to the rear of the boat so it is suspended above the candle. The boiler side, with the glue and folded parts, should be facing up. The bottom should be free from any glue or tape.
  18. With the boiler held in place above the candle, and the straws resting in the water, light the candle. The flame should be far enough that it is not touching the tin, but providing enough heat to steam the water in the boiler. As the steam builds, it pushes out the opening of the straw creating the momentum to power the boat. Priming the boiler and straw jets with water is a key part of success here. You may need to problem solve your boilers and innovate a better design. Using these directions as a starting point, you are on the path to success.


Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known.

HS-PS3-2. Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motion of particles (objects) and energy associated with the relative positions of particles (objects).

HS-PS3-3. Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy.*

HS-PS3-4. Plan and conduct an investigation to provide evidence that the transfer of thermal energy when two components of different temperature are combined within a closed system results in a more uniform energy distribution among the components in the system (second law of thermodynamics)

Conduct short as well as more sustained research projects to answer a question (including a self-generated question) or solve a problem; narrow or broaden the inquiry when appropriate; synthesize multiple sources on the subject, demonstrating understanding of the subject under investigation.

Reason abstractly and quantitatively.

MP.4 Model with mathematics.

HSN.Q.A.1 Use units as a way to understand problems and to guide the solution of multi-step problems; choose and interpret units consistently in formulas; choose and interpret the scale and the origin in graphs and data displays.

HSN.Q.A.2 Define appropriate quantities for the purpose of descriptive modeling.

HSN.Q.A.3 Choose a level of accuracy appropriate to limitations on measurement when reporting quantities.