A radiator Student activity Play

A radiator Whiteboard exercise Play

A ragworm Whiteboard exercise Play

A range of sizes Animation Play

A rational expression and its simpler form Animation Play

A rational function Student activity Play

A rectangular fence Animation Play

A rectifying system Animation Play

A rectifying system Whiteboard exercise Play

A rectifying system Student activity Play

A refracting telescope Whiteboard exercise Play

A refracting telescope Student activity Play

A refracting telescope Animation Play

A regular arrangement of the substituents Animation Play

A regular pentagon Student activity Play

A rigid solid and its motion Whiteboard exercise Play

A rigid solid and its motion Student activity Play

A rod Simulation Play

A rod cell's signal-transduction pathway Slideshow Play

A rotor Student activity Play

A rotor Animation Play

A rotor Whiteboard exercise Play

A roundabout Simulation Play

A ruler Animation Play

A savings account in a bank Animation Play