I begin this lesson by reminding students that we learned what energy is (the ability to do work) and that it can transfer from object to object. I want them to dig into their prior learning, and use that to define energy.
I remind students that we also learned that energy can be transferred from one form to another. I tell students that today we will be experimenting with how energy affects speed.
Next I show this video clip. I ask students to think about how much energy a rocket would need to blast into space as they watch this video.
Teacher note: A rocket has to travel 62 miles above the Earth to reach space at a speed of 25,000 miles per hour.
Students work with partners today to build and launch straw rockets. I give each partner balloons, straws, string, and tape. I place two chairs about 6 meters apart in the classroom and show students that they will replicate this outside to do the experiment today. I tell students that their task is to create a rocket that gets a balloon from one chair to the other chair.
Then I give students the materials (the yarn is pre-cut so most chairs will be about the same distance from each other) and time to develop a rocket system that would work. (See the resource section for complete directions.)
Teacher note: Some students may find this inquiry activity difficult. Students are used to being told exactly what to do. I resist the urge to "jump in and rescue" students as much as I can. Instead, I look for opportunities in which I can guide students through questions. Some questions I use are:
What do you know about the materials? What are you thinking might work? What does your partner think? Have you ever blown up a balloon before and let it go? What happened? How could you use that knowledge to help with today?
When it appears that most groups have some way of moving the balloon (not necessarily between the two chairs) I ask each group to demonstrate to the class what their group decided to do. The class then watches and observes as each groups demonstrates one "blast off" with their balloon rockets.
After all demonstrates, I give students about ten minutes more to refine and fix their balloon rockets based off of observations and knowledge gained from the class demonstrations.
When most students appear to have created a device that will move the balloon, I give time for all students to try their launcher for the class.
Students share with the class what they have discovered. As students launch their rockets, I reinforce the terms energy (energy – the ability to do work) and transfer of energy. I also remind students that there are different types of energy.
After the launches, I lead a brief discussion with the class how varying the amount of energy might change the process. I also talk with them about how changing the type of string or length of straw might change the outcomes.
Teacher background: From BioCircuits:
So how does it work? It's all about the air...and thrust. As the air rushes out of the balloon, it creates a forward motion called THRUST. Thrust is a pushing force created by energy. In the balloon experiment, our thrust comes from the energy of the balloon forcing the air out. Different sizes and shapes of balloon will create more or less thrust. In a real rocket, thrust is created by the force of burning rocket fuel as it blasts from the rockets engine - as the engines blast down, the rocket goes up!
For this lesson, I used informal formative assessment by observing students as they worked throughout the activity.
There are many ways to effectively observe students and gain information about skills and content they know. For this lesson, I did not have my usual record sheet and clipboard, and I missed it. Usually when I circulate around the room (or outside as in this lesson) I carry a clipboard with me in order to write observations down. This is extremely valuable and I refer to it often as I plan next lessons, small groups and assessments. It also serves as a way for me to keep track of "ah - ha" moments and moments of clarity students exhibit. When students have these kind of moments, they are just as important in my lesson and unit planning. While I often don't replicate the exact same lesson in the same year, this data becomes important for future years planning. It is helpful to look at the information and remind myself about lessons that really worked with students the prior year and ones that didn't. The lessons that didn't work get revised and edited in order to be more successful.
In this lesson, some of the things I would have written down was that many students seemed to be inexperienced with the act of letting a balloon go and what happens to it. In the future, this might be a pre-activity I would do before the lesson.