Use small pulleys to pull up a weight, and feel the difference in force with different numbers of pulleys.
Science content (2016 curriculum):
Physics: Motion and Forces, Newton’s Laws, Gravity (K, 2, 6)
Physics: Simple and complex Machines (5)
Science topic (2005 curriculum connection):
Physical Science: Force and Motion (grade 1)
Physical Science: Forces and Simple Machines (grade 5)