  Previous research has found that introductory physics students perform far
better on numeric problems than on otherwise equivalent symbolic problems. This
paper describes a framework to explain these differences developed by analyzing
interviews with introductory physics students as they worked on analogous
numeric and symbolic problems. It was found that information about the physical
situation, as well as the problem solving process are represented in subtly
different ways in numeric problems compared to symbolic problems. In almost
every respect the inclusion of numbers makes information more transparent
throughout the problem solving process.
