Andes

• Outer loop: The Andes physics tutoring system (http://www.andes.pitt.edu/) helps students learn how to solve physics problems (K. VanLehn et al., 2005; K. VanLehn et al., 2002).
• Inner loop: The student solves the problem by making steps similar to the ones they would make if solving the problem with pencil and paper. One kind of step is to type an equation into one of the numbered boxes in the right window. Another kind of step is to draw a Cartesian coordinate system, such as the one showing in the lower left. A third kind of step is to sketch a vector, then fill out a dialogue box that defines it. A vector-drawing operation was in progress at the time the screen shot was taken, so its dialogue box covers part of the screen.
• Every time the student makes a step, Andes gives immediate feedback. For most types of steps, Andes merely colors the step green if it is correct and red if it is incorrect.
• Step analysis: Like the Algebra Cognitive Tutor, Andes analyzes non-equation steps by precomputing anticipated steps and matching the student’s step against them
• However, this method does not work for the equation steps because there are too many anticipated equations to generate