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STACK (System for teaching and assessment using a computer algebra kernel) is a leading assessment system for computer-based practice and testing in STEM subjects and is available in Moodle and ILIAS as a question type.

The core features of STACK are the input of mathematical expressions such as function terms or matrices and the checking of student answers.


In order to evaluate mathematical expressions and check them for relevant properties, STACK uses the computer algebra system Maxima.
Checking for properties can be used as a basis for evaluation and feedback. Such properties can be:

  •     Is the expression equivalent to the solution?
  •     Is the expression completely simplified?
  •     Is the expression given in a certain form (e.g. factorised, multiplied out,...)?


JSXGraph is a browser-independent JavaScript library for interactive geometry, function graphs, diagrams and data visualisation in theWEB browser.

JSXGraph is integrated into STACK and can also be used for input, so that students can, for example, manipulate graphs and receive feedback on them.