Reports the results of a study of 135 high school students who were randomly assigned to long, medium, and short frame-length treatments of programmed United States History instruction. Results showed significant independent effects for frame length and IQ, in addition to a significant effect for the interaction between the two. (JDH)

Phrases of uncertainty used by social studies teachers in high school history courses negatively influenced achievement for students of all ability levels. A link was found to exist between frequency of teacher uncertainty phrases and student perception of the teacher as a knowledgeable authority on the topics covered. (Author/RM)

Secondary students who read an economics lesson silently scored significantly higher than students who received an oral presentation of the lesson. A significant interaction between lesson organization and student ability level indicated that highly organized economics lessons increase student learning under certain ability level conditions.…

This study investigates whether college students can accurately distinguish between lessons taught in clear and unclear manners and what the effect of a low clarity lesson is on achievement at the knowledge (recall) level. Concluded that students can distinguish between high and low clarity lessons and that there is no causal relationship between…