Clarity College students (N = 41) were'randomly assigned to pne of two groups defined by the teacher's clarity in the lesson, i.e., high clarity versus low clarity presentation on genetics. After the lesson, the subjects completed a test on the contents of the lesson and then rated the lesson presontation. Students in the high clarity group achieved more (although not significantly) than 'students in the low clarity group.. Student perceived the high clarity lesson as significantly clearer than the low clarity lesson. -These findings are discussed in relation to previous reSearch on teacher clarity.