Often a teacher wants to spur students to think more deeply about a topic. Instructors sometimes get deeper thinking through class discussions, by using group work, or with carefully constructed homework problems or laboratory experiences. Small whiteboard questions can also be used to get students to look beyond memorized rules or algorithms.

One example is an instructor who saw that students had memorized that the period of a simple harmonic oscillator was amplitude independent, but didn't know why this so. The students also tended to over-generalize to any sort of repeated motion. The instructor asked the students to write on their whiteboards an argument for why the period a spring should increase with amplitude, and a second separate argument for why the period should decrease. This caused students to see the balancing factors that lead to the amplitude independence.

As a follow-up, the instructor asked students whether two perfectly elastic balls, one droped from 110 cm and one dropped from 120 cm would bounce with the same period. The vast majority of the class responded that both balls would stay synchronized. This over-generalization of the rules of simple harmonic motion allowed the instrutor to then focus on the special characteristics on a simple harmonic oscillator. The students carefully paid attention to the arguments about potential wells in a way they never had in previous years, when the whiteboard question was not used.

* Draw the equipotential surfaces due to two point charges

* Make an argument for why amplitude should increase the period of a vibrating spring and a separate argument for why the period should decrease.