Learning science through writing: The role of rhetorical structures

In a 2 x 2 between-groups study, 85 preservice education students observed a science experiment concerning either buoyancy or the forces acting on a s tationary object. Each student then wrote an Initial explanation of the phe nomenon followed by a journal-style note, then a final explanation. For eac h science experiment half the students received a list of strategy prompts intended to facilitate learning through writing, and half wrote without the se prompts. Forty-three percent of the "buoyancy" students and 14% of the " forces" students increased the complexity of their explanations during the writing interval. Strategy prompting did not increase explanatory gains. Te xtual analysis showed that for the buoyancy problem, writing comparisons am ong trials and explanations of individual trials correlated with explanator y gains during the writing interval. For the forces problem, writing a conc luding summary correlated negatively with explanatory gains. Qualitative an alysis suggested that rhetorical structures (explanation, comparison, argum entation, and summarization) contributed to learning during three phases of building explanations: reviewing experimental trials, analyzing these tria ls to identify causal variables, and generalizing these analyses to form ne w explanations. These rhetorical structures stimulated, rather than structu red, the construction of new knowledge and mapped onto the logical operatio ns through which writers coordinated hypotheses and experimental trials in a many-to-many, rather than a one-to-one,fashion.