Analogies between old and new concepts are common during classroom instruction. Previous transfer studies focused on how features of initial learning guide later, spontaneous transfer to new problem solving. We argue for a shift in the focus of analogical-transfer research toward understanding how to best support analogical transfer from previous learning when children are engaged in new learning episodes. Such research may have important implications for teaching and learning in mathematics, which relies heavily on analogies between old and new information. Some existing research promotes supporting explicit connections across old and new information within an analogy. Alternatively, we argue that teachers can invite implicit analogical reasoning through warm-up activities designed to activate relevant prior knowledge. Warm-up activities close the transfer space between old and new learning without additional direct instruction.