Representations such as formal notations and diagrams routinely figure
in students' learning of mathematics and science. However, in light o
f the extensive research on students' misunderstanding in these subjec
t matters, it is reasonable to ask whether other kinds of representati
ons might help students to reach better understandings. Indeed, a numb
er of educators have developed innovative representations, typically o
n computers, that supposedly foster understanding through suggestive v
isual analogies and 'microworld' to manipulate. Evaluative research on
these 'new look' representations as well call them suggests that they
indeed can help students to understand. In this review, we focus on e
xactly how these representations aid understanding. We propose that th
ey do so by facilitating the learner's construction of explanations, j
ustifications, predictions, and the like. These constructions require
search in problem spaces, in the sense of Newell and Simon (1972). The
representations in question reduce the cognitive load of such searche
s, clarify the structure of the problem spaces that need to be searche
d, and make certain moves in the problem spaces more immediate. We inv
oke Gentner's (1983) theory of 'structure mapping' to explain how thes
e advantages are attained. We also examine several characteristics pit
falls of representations in this style.