Educators aim to equip students with learning strategies they can apply when approaching new problems on their own. Teaching design-thinking strategies may support this goal. A first test would show that the strategies are good for learning and that students spontaneously transfer them beyond classroom instruction. To examine this, we introduce choice-based assessments (CBAs). CBAs measure how people learn when there is minimal guidance and they must make decisions as independent learners. Here, sixth-grade students completed multiple design activities that emphasized either seeking constructive criticism or exploring a space of alternatives. Afterward, they completed the CBAs, which measured strategy transfer. Results showed that lower-achieving students benefitted most from instruction, exhibiting a relative increase in their use of design-thinking strategies. In addition, strategy choices correlated with prior achievement measures and appeared to mediate performance in and learning from the CBAs. The choices to use the two strategies themselves were not correlated, which indicates that they are not subsets of a larger construct, such as growth mindset. In sum, CBAs enabled a double demonstration: design-thinking strategies may improve learning and problem solving, and design-thinking instruction may improve the likelihood of lower-achieving students choosing to use effective strategies in novel settings that require new learning.