Investigating best amount of water to fly a bottle rocket

This activity is designed to help students learn to carefully record data and to observe what happens to the rocket with varying amounts of fuel(water). Students will learn concepts about force and motion, and see real life applications to Newton's Laws of Motion. Students will use critical thinking skills to decide from results of the experiment how much water to use to keep bottle in air the longest possible. Students will use graph making skills to present the data. Vocabulary words used and learned should include: force, altitude, pressure, motion, and velocity.

This activity will take place during a unit on space. This activity is designed for students in grades 6-8. A bottle launcher and bicycle pump is needed. The activity is designed to be completed in two-three class periods. 10-15 minutes time is spent in the classroom discussing the rockets, showing how to record data, and class behavior expectations. Then class time will be spent outside in a large open area where the bottle rockets can be safely launched. Launching may take one-two days depending on how many rockets are used. Day three will be spent in the classroom, recapping what was observed and completing the graphs.

The class will work as a whole group. Pop bottle, water, launcher, bike pump, stop watch, and data sheet will be provided by the teacher.

Day One: students will discuss what they predict will happen when the amount of water in the bottle rocket is changed. Students will predict which proportion of water to air will make the bottle go the highest. Students are to draw how much water should be placed in the bottle for it to stay in the air the longest. Students should explain why they think this. Class will go to an outside field where the water bottles are to be launched. Before each launch, students will measure how much water is placed in the bottle. Teacher will place the bottle on the launcher. A student will use the bike pump to build up pressure. Another student will time the rocket from when it leaves the launcher until it hits the ground. An area will be designated for all spectators. Students will record results: how much water used, how long bottle in air. As the group collects data, questions will arise to determine how much water should be used to record the longest flight. Discuss why bottle needs water at all, why it is not in air longest with the bottle completely full of water. Day two: Discuss results and fill in graph with the data. Students are also to write what they observed and learned from this lab.

Safety rules to discuss with students: All are to remain in a designated area, away from and behind the launcher until the bottle has landed on the ground. One designated student will retrieve the bottle. This should be done on a calm, fairly warm day. I have done this activity with my class every year, at the beginning of school, except we have not timed how long the bottle remains in the air. We also did not precicely measure the water amounts. In the past we have just changed water amounts, and watched how far the bottle flew without making any scientific measurements. Adding this measurement will help the students determine in a scientific manner rather than just gut feeling how much water to add so the bottle stays up longest. This will make the activity a scientific experiment with one controlled variable.

Students will complete data sheet and graph of the data. Data collected will be: amount of water used, time bottle in the air. These will be the two axis for the graph. Students will then write a summary of what they observed and learned from this lab. Summary should be a minimum of 3 paragraphs.

II. Physical Science.D.1,3; I.B.1,2,3,4