Student Preconceptions of Levers and Pulleys
Levers
Describe tools used to determine student preconceptions:
1) six foot board: used as a pre-assessment of concept awareness
2) nail in board and a hammer
Description of a student preconception (naïve conception, misconception, incomplete conception):
1) When asked how to use a six foot board to lift their teacher, students often put the fulcrum in the middle of the board rather than at the load end.
2) When asked how to hold a hammer, students often illustrate holding the hammer closer to the claw part of the hammer to remove a nail. This misconception is based on their knowledge of load and effort.
Correct conception by the end of the unit for both 1) and 2):
Students will have a better understanding of the concepts of load and effort. The essential concept of a class 1 lever is that a fulcrum moved closer to the load reduces the amount of effort needed to perform the task.
Pulleys
Describe tools used to determine student preconceptions:
Students are given the essential parts of a pulley system and are asked to assemble those parts into a pulley system. This initial pre-assessment might include a piece of string, a wheel, and a load (block). Students may use any additional materials they feel are necessary.
Description of a student preconception (naïve conception, misconception, incomplete conception):
Students have an incomplete preconception regarding how to assemble the pulley parts into a working system.
Correct conception by the end of the unit:
Students will have learned how to assemble a pulley system to be able to reduce the amount of effort needed to lift a required load. They will have also learned that for each additional pulley added to the system, the effort required to lift a load is reduced by one half.