protons, electrons, how different elements can have different isotopes, the periodic
table, photosynthesis and cellular respiration. He worked his way through different
concepts one by one until he finally ended up with ‘chemical compound’. In the
lesson, Mark was very attentive to students’ ideas and previous conceptions and in
order to increase students’ interest he tried to connect to their ideas as much as possible,
without any predestinated plan. He went from micro to macro providing one
example after another. However, in his attempt to use a lot of different examples, he
lost the connection to the intended object of learning. For example he discussed different
elements and how to recognize the different elements only through looking at the
periodic table without really relating to the atom model, mixtures and chemical compounds
with the students. In his interaction with the students he put a lot of effort into
building on students’ earlier experiences. As such, his endeavour in lesson 1 to catch
students’ ideas and conceptions sometimes lead him away from the actual object for
learning.