Via Joanne Jacobs: Randomly calling on students can mean students pay more attention and prepare more for class.
It took a college (Univ. of Florida) study to determine this? This may rank up there (but not all the way) with those goofy AP "study" headlines -- you know, the ones like "Study: Eating a fatty diet can lead to health problems." This always seemed like pure common sense. Teachers usually have students who always raise their hands to answer questions, and if the teachers limited themselves to just these students, the others in class know they can slack off. I recall only one college prof. of mine using this strategy (an economics professor, who was quite good -- which is a definite compliment considering I didn't like economics), and it made me prepare meticulously for each and every class -- especially since early in the semester I was embarrassed twice for not knowing the answer when randomly called on!
I've utilized the "random calling" on students in my classes since day one, year one. Ironically, I was once criticized by a "higher-up" during an observation for "ignoring" kids who "had their hands up" to answer a question. In the only written reply I've ever made in response to an observation, I noted exactly why I don't always call on kids with their hands up. It's essentially what the U. of F. study quotes:
The interview data from the teachers and students shows this technique helped students do those things that we know help them to be successful in school – paying attention, being prepared for class, staying focused and doing homework.
The reply to my reply was quite favorable!