Blast off the wet way

This lesson takes 6–10 days and includes math classes in which students will serve as observers and will calculate the height that the rocket reached and time elapsed. In the science class the students will design, build, launch, and do a detailed analysis of the acceleration, speed, and force produced by water-filled two-liter rockets.

A lesson plan for grade 7 Science

By Jack Curtis

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Learning outcomes

The students will:

• explore Newton’s Laws of physics
• design two-liter bottle rockets for launch
• calculate the rate of acceleration for their rocket’s launch
• calculate the height attained by their rocket

Teacher planning

Time required for lesson

6–10 days

Materials/resources

• two-liter bottle in good shape (no holes. cracks, or dimples)
• rocket launching device
• triangulation graph for height calculation
• stop watch
• water source
• measuring device for water amount per launch
• scales for measuring weight of rocket
• scissors
• different types of paper for fins and nosecone

Technology resources

Internet access to see other methods of rocket design, along with desktop computer for report writing. Digital camera to record activities during launch day.

Pre-activities

Prepare the students by introducing Newton’s Laws of Motion. Preview with a word search puzzle to allow a low pressure way to gain the vocabulary knowledge. Demonstrate the Laws of Motion with simple experiments showing friction, force, acceleration rates, and opposite and equal forces.

Safety should be reinforced before all labs that have projectiles involved. The launchers must wear goggles, and a safety area of at least ten yards in all directions, where no observers may stand, must be established.

My students were already trained in the triangulation methodology by the math department, but you can teach this skill using written instructions from a worksheet. Pre-algebra classes teach this skill in some school systems.

Activities

1. Have the students bring empty two-liter soda bottles from home. Supply various materials for the nose cone and fins. Show several designs by having the students explore websites done by other schools on the internet. Allow free rein in the design of these elements.
2. Either hand off the responsibility of tracking the height and length of flight time to another class (math or social studies for example), or teach the class to measure the height using similar angle triangulation to estimate the greatest height attained and show the best methods for timing the total flight time.
3. There are many methods of launching; I found a dual launch kit in one of the science catalogs. Many other teachers have plans for fabrication of launch devices on the internet. Launch method can be a variable as far as total efficiency is concerned. If you are mechanically inclined this could also be tested.
4. Launch day should be identified to the rest of the school for safety reasons and to allow teachers and classes to act as launch observers. Set up at least three height observation stations in different positions, and combine these to attain the average height. The timers (as many as needed to involve all of the students) should be located near the launcher (one of the students whose rocket is being launched) to be able to get an accurate flight time.
5. Remember Safety Measures—no one around the launching pad except you (or your designated assistant), keep rockets aimed away from people or buildings, and follow all other general safety rules about running, fooling around, or misbehaving.

Assessment

Assessment will be a combination of a rubric for the design and build classes. This rubric will include use of materials, time on task, and behavior. Launch Day will be graded on a similar rubric. Analysis of the entire class’ launch data should be done in small groups to allow the pairing of good math students with those who need help. A data analysis sheet will be turned in for final grade on this project.

Supplemental information

Remember to enforce the safety rules because these rockets will move very quickly during the launching process, and they can do damage to humans or buildings.