The Effects of Vocabulary Instruction on Fifth Grade Science Achievement Meghan Connelly May 2004 The purpose of this study was to examine the effects of vocabulary instruction on science achievement. This study was done in 2004 with four fifth-grade science classes at a public elementary school. In the study, two groups of students were used, one containing average readers and one containing the higher and lower ability readers. A pre test was given to both groups at the beginning of each week. Group one received the intervention on the first week, and the second group participated in the second week. During the intervention, the students engaged in five to fifteen minutes of vocabulary development based around possible sentences and semantic mapping. Both groups read the same articles and completed the same scientific investigations. A total of four quizzes, including the pre tests, were given. There was no significant difference found between the post test averages of groups one and two after the first week. However, a significant difference was found between the post tests the second week. Further research is warranted to determine if the strategies are successful with varying degrees of prior knowledge and with students of different ability levels.