Abstract

This study investigated the extent to which vocabulary knowledge and class size would predict students' achievement in summary writing in Iwo Local government Area of Osun state. The study adopted the descriptive survey research design of the correlative type. The participants were 507 SS2 students from nine randomly selected senior secondary schools in Iwo Local Government area. Purposive sampling was used to select three schools with medium, low and large class size each. The instruments used for data collection were Achievement Test in Summary (r=0.87) and Vocabulary Knowledge Test(r=0.74). Data were analysed using Pearson Product Moment Correlation and Multiple regression. Results showed that vocabulary knowledge (r=0.242) and class size r=0.305) had positive relationships with students' achievement in English summary writing. The composite contribution of the two variables (F = 38.380; P<0.05) was significant. Vocabulary knowledge(â = .200) and class size(â= .275) also made relative (2,504) contributions to the dependent variable. Based on the findings, it is recommended that government should build more classrooms so as to make the implementation of smaller class size possible in schools, while teachers should encourage students to develop their vocabulary knowledge making them read supplementary readers.