Spool Rolls Toward the Pull
The spool may roll toward your hand or away depending on angle.
Teaching & key ideas
What you do: Pull string at different angles.
What students see: The spool may roll toward your hand or away depending on angle.
Why it works: The pull creates torque about the contact point; direction depends on geometry.
Question to ask: Why can pulling right make it roll left—or right?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: Why can pulling right make it roll left—or right?