This research aims at examining the effectiveness of designing an educational environment based upon cartoons to develop some musical concept among primary fifth year students. Achieving this aim, the researcher designed an educational environment using Ashour model. In doing so, she used lots of instruments including computer, over head projector, school course books, and models. Lots of famous cartoon characters have been used. The researcher adopted the quasi- experimental design. Participants included 40 students divided into a control group and an experimental one, with 20 students in each group. The musical concept’ test has been validated by a group of jurors, and then it was pre- and post- administrated to participants. Results indicated that 1) There is a statistically significant difference between the mean scores of the experimental group’ pre- and post- musical concept’ test in favour of the post- test’ results, 2) There is a statistically significant difference between the mean scores of the experimental group and control one’ post- musical concept’ test in favour of experimental group’ results, 3) There is no statistically significant difference between between the mean scores of the experimental group’ post and traceable tests, and 4) There is effectiveness in designing an educational environment based on the cartoons strategy to develop some musical terms among primary fifth year students by calculating Modified Blake´s Gain Ratio. This research is divided into two parts. The first part includes introduction, aims, significance, delimitations, hypotheses, previous studies, and literature review. The second part represents the practical part including procedures, results, recommendations, references, appendices, and summary. Keywords: designing an educational environment, cartoons, musical concept.