We sketch an outline of a model for analyzing the use of ICT-tools, in particular CAS, in teaching
designs employed by ‘generic’ teachers. Our model uses the business economics concepts out- and
insourcing as metaphors within the dialectics of tool and content in planning of teaching.
Outsourcing is done in order to enhance outcome through external partners. The converse concept
of insourcing refers to internal sourcing. We shall adhere to the framework of the anthropological
theory of the didactic, viewing out- and insourcing primarily as decisions about the technology
component of praxeologies. We use the model on a concrete example from Danish upper secondary
mathematics to uncover what underlies teachers’ decisions (deliberate or colloquial) on
incorporating instrumented approaches.