Although the consensus seems to be that high-school-level introductory engineering courses should focus on design, this creates a problem for teacher training. Traditionally, math and science teachers are trained to teach and assess factual knowledge and closed-ended problem-solving techniques specific to a particular discipline, which is unsuited for teaching design skills for open-ended problems that may involve multiple engineering disciplines. Instead, engineering teacher training should use the more fluid framework of adaptive expertise which values the ability to apply knowledge in innovative ways as well as recall facts and solve problems using conventional techniques. In this study, we examined a 6-week program to train math/science teachers to teach high school design engineering. For each curriculum unit, we had a pre-posttest to assess the teachers' factual knowledge and ability to solve typical problems (termed ''efficiency'') and their ability to apply their knowledge to reason through open-ended problems (termed ''innovation''). In addition, we conducted a pre-posttest to see whether teachers' attitudes and beliefs related to adaptive expertise changed over the course of the program.