Purpose: The purpose of this paper is to investigate the effect of an embedded pedagogical agent into a tutorial on achievement. Design/methodology/approach: Research methodology is designed according to the post test control group model in which the experimental group (69 students) was exposed to a tutorial with an embedded pedagogical agent; control group (56 students) was exposed to the same tutorial without a pedagogical agent. The tutorial was developed by the researchers as educational software on the unit "Discovering Space" for 6th graders. Findings: The data analysis showed that the experimental group performed significantly better than the control group which indicated that using a pedagogical agent in a tutorial has a positive effect on the achievement. Another finding related to the gender differences is that girls performed better than the boys. Research limitations/implications: This research has some implications for designing educational software. Embedded pedagogical agent is improving learning by providing interaction and motivational support. So designers must take in consideration of using animated pedagogical agent in educational software. The long-term effects of interaction were not explored in this study. Practical implications: It is important to choose a suitable agent according to domain and age group. The case of "whether the pedagogical interface agent should be intelligent or not" is also a subject open to debate. Intelligent agent holds the behavior of learner and adapts itself specifically to the learner. Originality/value: This research has original value for instructional designers and educational software developers. Also this research has contributed to human-computer interaction domain.