Ongoing work toward developing a learning environment that will perform real-time diagnoses of students' difficulties in solving mathematical word problems is described. The learning environment designed consists of a microworld and expert modules. The microworld (or toolbox) is a collection of mouse-driven interfaces that facilitate a transition between manipulative models of arithmetic word problems (such as those using physical blocks) to the more abstract symbolic models (such as an open-sentence equation). The expert module is composed of mathematical and linguistic problem solving models. A linguistic or reading expert first generates a conceptual representation of the actions and sets in a word problem, and the mathematical expert then attempts to assign part-whole roles to the conceptualized sets and arrive at a numerical model. The focus is on the expert reading model. A conceptual analyzer, EDUCE (Explaining Discourse Understanding with Conceptual Expectations), reads English word problems and generates conceptual representations of the quantities and actions in the word problem. By altering its linguistic abilities, the learning environment will perform real-time diagnoses of students' erroneous solutions and give the teacher hypotheses of potential misunderstandings. In its instructional role, EDUCE is designed to explain the role of certain words and phrases in a word problem. In its cognitive modeling role, it helps explain why some problems are harder than others. Four tables are included. (SLD)