The present study was conducted to investigate the effect of web based instruction, on achievement, in computer education of VIII graders. Experimental method was adopted employing Pre-Test Post-Test control group design. Sample of 125 students based on scores of intelligence test, was classified into high, average and low intelligence groups. The high and the low intelligence groups were ignored and only average intelligent students were further divided into control group and experimental group i.e. conventional teaching group and web based instruction group respectively, so as to equate both the groups on the parameters of intelligence. The investigator's self constructed website, in word press web hosting, was purchased to make the website accessible via the world wide web. Original text book content was transformed into online learning material. Main goal was to implement an easy way to use web based instruction package. The results were derived quantitatively. The results showed that there was a significant difference in the mean scores of achievement of students of both the groups due to difference in mode of instruction. Students of web based instruction group performed better than the conventional method group. Further, gender differences were also evident in the results. Boys were less attentive during the process, whereas girls were more enthusiastic towards the experiments and were fully involved in the process. The results obtained from the application/evaluation of a set of educational activities have been quite encouraging, indicating that the simulation program and the context of the activities can effectively support and enhance the learning process.