Diagnostic Testing

Educators suggest that diagnostic testing in secondary schools is very important. I agree. However, this is difficult if not impossible for many teachers of science and mathematics to undertake. Suppose a science teacher asks his/her class what is light. Assume the student replies by suggesting that light is a steam of particles. How can that teacher continue unless he/she is familiar with the two major models for light? Suppose a science teacher asks his/her class what is heat. Assume a student replies by suggesting that heat is related to how fast a particle moves. How can that teacher continue unless he/she is familiar with the two major models for heat? I suggest that numerous teachers of science and mathematics are reluctant to ask such open ended questions because their knowledge of the subject matter in these two disciplines is lacking.