This PBL is super easy to implement. I have included 1-2 investigations for each simple machine. Students have a Scientific Notebook to record their data for each investigation. Each investigation includes a materials list and directions. The PBL concludes with students using what they learned from their investigations to create a machine using at least 2 simple machines. An Inventor's Journal is also included to prompt students with revising their machine.
Investigation #1 students build two incline planes of different lengths but of the same heights.
Investigation #2 students build 2 incline planes that are the same lengths but different heights.
Investigation #3 students build a lever and they move the fulcrum. They chart how much weight is needed to move the lever.
Investigation #4 students move a wedge and blunt object through sand/rice and record their observation.
Investigation #5 students compare a thin wedge and a thick wedge.
Investigation #6 students create a four wheeled cart and measure how much force is required to move a heavy object.
Investigation #7 students measure how much force is needed to lift a heavy object using no pulley, 1 pulley, and 2 pulleys.
Investigation #8 students observe how a screw works and compares it to an inclined plane.
On a time crunch? This PBL can be completed in 2 weeks. If you set up the investigations as centers, students can complete all 8 investigations in a week and they can work on their inventions the following week.
This PBL is easy to use in the primary classroom but contains complex problem solving that is also appropriate for intermediate grades.