The purpose of this study is to explore the effects on learning achievement of English listening & reading comprehension and learning motivation by applying “Cool English” online teaching materials, set up by the Ministry of Education (MOE), to 4th graders’ English instruction. A quasi-experimental design was adopted in this study, and 90 4th graders in a district of Taichung City were selected. Forty-five sample students were defined as the treatment group, and the 45 belonged to the control group. A ten-week teaching experiment was conducted on the treatment group, while didactic e-book teaching was done on the control group. The data of pre-test and post-test scores from the listening & reading comprehension test were aimed at analyzing students’ English learning achievement. At the end of the teaching experiment, the data of Instructional Materials Motivation Scale were collected to examine the difference in students’ learning motivation. The conclusions are as follows. 1. By applying “Cool English” online teaching materials to English instruction, students’ learning achievement of both listening and reading could be improved. For the scores of the listening and reading test, the treatment group was higher than the control group. There is a significant difference between two groups, but there is no significant difference when statistically testing the listening scores and reading comprehension scores respectively. 2. There is a significant difference in the learning achievement of both groups, as all students were instructed by using computers and information technology. 3. There is no significant difference in students’ whole learning motivation, but there is a significant difference in two motivational factors: “attention” and “satisfaction”. Finally, the findings of this study offer some evidence for reference for English teachers at elementary schools who want to apply e-Learning resources to their instruction.