ABSTRACT
The use of the modals of obligation and necessity – must should and quasi-modals have to and need to is compared in laboratory reports written by South African science students for whom English was a second language (ESL) and the British Academic Written English Corpus (BAWE) (Nesi et al 2008). The purpose of laboratory reports is for students to report on their experimental work. This involves explaining findings and includes assessing how likely their explanations are to be factual. Students also report on what they had to do what must or should be done and what the molecules apparatus etc. need to do in the experiment. Findings show that ESL writers make significantly more use of these modals particularly must and should than do the L1 writers of the BAWE corpus. In their use of modals the ESL writers make considerably more appeals to authority both their own authority and that of others and make substantially more use of subjective modality compared to the BAWE writers. Based on these findings suggestions for pedagogy are proposed.
