This paper is a response to Maria Andree's paper. Andree tells in the paper how mistakes in practical lessons may be critical events to change students' attitudes in regard science. While traditionally mistakes in practical lessons could obligate students to repeat the experiment in order to get the "right result" in the paper we have a good example how we can use the incident to potentiate students' participation. In my response I illustrate how transferable is what Andree speaks about but I put forward further reflections about the traditions that may act as impediment for students' participation. I thus suggest that the critical paradigm should be a component in reflecting about science classroom practices in order to alter the traditions.