I start the lesson with a demonstration of my hand generator. I use the strategy of modeling to help my students understand how kinetic energy is converted to electrical energy. Students are given the opportunity to move the crank to light the bulb. I've found that to give them the challenge, “Who can keep the light going the longest amount of time?” keeps more students engaged. Students time one another to determine the winner. After the investigation, students talk about themselves and the difficulty of the activity. This is an important part of developing a culture of ownership, which helps to make the learning resulting from the activity to stick.
A parent built a bike on a roller and set it up to a motor. I use this as a model for understanding energy transfers. Instead of the bike, you can build or buy hand crank generators for around $60. For the bike, we bought a workshop light stand to plug in different types of light bulbs. This set up would also work with hand crank generator, to give your students the opportunity to generate energy to light up different types of lights.
I show students the bike and the motor. My strategy is to discover science concepts and I offer students an unusual model to intrigue them. I tell them we want to investigate the differences between the kinetic energy needed for different types of light bulbs.
I ask, “I need your help. How should we test this? What problem do you want to solve?" The purpose is to help students create scientific investigations as they begin Developing an Investigation. I support the students as they learn to plan an investigation collaboratively (Science Practice #3). Using mini-white boards the class collaborates on ideas for problem, hypothesis, procedure, controls, independent, dependent variables and a data table. I take the ideas and place them in a document. I use this strategy because when my students design the investigation, they have much more ownership of the results.
As well as developing the elements of an actual investigation, and practicing data collection, an additional purpose of this investigation is to make a real world, as well as an emotional connection, to energy use.
My evaluation strategy is to promote learning by writing a conclusion. Using the following prompts, students answer conclusion questions.
Was your hypothesis correct? (As students talk about their thinking they make more connections to their learning and investigation experience.)
What does this lab teach you about light bulb energy? What surprised you about this lab? (Here I am asking them to assess their own learning. Using this information I can address misconceptions and confusion.)
Explain why government agencies ask citizens to reduce their use of incandescent bulbs? How could your data help with our current environmental problems? (The purpose here is to promote authentic learning and apply it to real life problems and solutions.)
How could this information help with our current environmental crisis? (My strategy is to connect what the students are learning to real world problems.)
I've annotated these generator lab student samples, so that they can be useful to you when evaluating your students' work.