Mathematics and science have similar learning processes (SLPs) and it has been proposed that courses focused on these and other similarities promote transfer across disciplines. However, it is not known how the use of these processes in lessons taught to children change throughout a preservice teacher education course or which are most likely to transfer within and between disciplines. Three hundred and ninety lesson plans written by 113 preservice teachers (PSTs) from 10 sections of an elementary mathematics/science methods course were analyzed. PSTs taught an eight-lesson sequence to children: five science lessons followed by three mathematics lessons. The findings suggested that: (a) PSTs needed to only teach three mathematics lessons, after five science lessons, to reach the same number of SLPs used in the five science lessons; (b) some SLPs are highly correlated processes (HCPs) and are more likely to transfer within and between science and mathematics lessons; and (c) PSTs needed to teach no mathematics lessons, after four science lessons, to reach the same number of HCPs used in the four science lessons. Implications include centering courses on multiple and varied representations of learning processes within problem-solving, and HCPs may be essential similarities of problem-solving which promote transfer.