This study explores the quality of student-teachers' (STs') verbal communication during their teaching practice on the "Studies for the Environment" subject, and identifies potential factors affecting it. Forty-one teaching sessions were analysed revealing that STs dominate classroom talking by having almost an equal number of utterances with their students. Moreover, only about one-third of STs' sentences are questions, with the majority of them being factual (38%), while probing (18%), higher order (18%) or divergent (6%) questions were much less frequent. In addition, although teaching sessions were addressed to very young children (6-9 years old), only a minor percentage of questions were stimulating their emotions (5%). STs' questioning seems to be independent from the class size, grade level and topic of instruction, while STs' expressed utterances are significantly higher in smaller classes. A classroom verbal communication pattern was also developed from the available data; however, it is confined within the Greek context.