Scientists write about their observations and research with enough detail for others to be able to critique what they have done. Descriptions in science tend to be factual and objective. Students need practice to be able to describe things in this particular way.
Understanding and using the literacy practices of science supports students to think in new ways and supports students to become scientifically literate, i.e., to participate as critical, informed, and responsible citizens in a society in which science plays a significant role. (This is the purpose of science in NZC.)