The aim of this study is to examine a verbalization activity between students with a role of 'gatekeeper' and students with a role of 'end-user'. We examined the second graders' conversations in science classes in at the lower secondary school level, and examined their level of achievement. We compared the contents of the conversations between different students with different achievement levels. The findings of this study are as follows: the students taking a role of 'gatekeeper' appeared spontaneously; the students with a role of 'gatekeeper' and students with a role of 'end-user' talked ...