The purpose of this study was to investigate the instructional effectiveness of animated signals among learners with high and low prior knowledge. Each of the two treatments was presented with animated instruction either with signals or without signals on the content of how an airplane achieves lift. Subjects were eighty-seven undergraduate students from WuHan University of Science and Technology in Central China. Among them, 40 were from the College of Education; the other 46 were students from the College of Mechanical Engineering. The participants were randomly assigned to signaled animation or non-signaled animation groups. Prior to the experiment, the participants filled out the prior knowledge questionnaire to measure their background knowledge on the content. Upon completion of the treatments, subjects were administrated two different tests. The retention test contained one question that was to measure the amount of material retained by the subjects. The learning transfer test contained five questions, was to measure the subjects' ability to apply the learned material in simulated situations. Upon completion of the tests, the adapted NASA TLX was used to measure the subjects' cognitive load that related to the type of animation. The time that subjects viewed the animation was also recorded for analysis. The same tests were administrated three days later. Results indicated that there were no significant differences for animation with signals or without signals in the retention tests and transfer tests. The mental load related to the types of animation was not significantly different, and the study time was not significantly related to the type of animation. The claim that animated signaling enhances learning was not assumed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]