Increasingly, students learn to use computer based tools to support their coursework in science and technology. A common educational strategy is to introduce the new tool along with new course material, having students learn the tool and the material simultaneously. We looked at how two simultaneous learning goals affect students' learning of a computer algebra system (CAS), a tool increasingly used in science and technology education. The study described involved teaching a group of students some basic CAS commands through one of two sets of instructional materials that used different contextual examples, based on either familiar or unfamiliar mathematics, which theoretically imposed different levels of cognitive load based on predictions of cognitive load theory. The students' learning of the CAS concepts was tested and their workload during learning and testing was measured. We showed that the students in the familiar math case performed better on a test of CAS concepts and that they reported a lower workload when completing the test. This result was consistent with the predictions of cognitive load theory. This study points to the potential importance of managing the cognitive load of instructional material when training students in the use of advanced educational software systems.