Purpose: Elementary school students are expected to participate in science learning settings that place high demands on skill with certain types of grammatical structures, including complex sentences. This research note aims to clarify the types of complex sentences that are evident in a general education science curriculum across the elementary school years in order to assist clinicians and others in better understanding the specific language demands of science learning in the classroom. Method: I analyzed all sentences within children's texts and suggested teacher scripting from the first-, third-, and fifth-grade science units of a commonly used general education curriculum aligned to the Next Generation Science Standards. We determined the frequency and type of complex sentences that were present for each type of material (text, teacher scripts) and grade level. Results: Complex sentences are evident in both children's texts and suggested scripting provided to teachers at all grade levels. The rate of complex sentences in children's readings is higher in third- and fifth-grade texts than in first-grade texts. Complement clauses are common throughout, and adverbial and relative clauses are more frequent in third- and fifth-grade texts than in first-grade texts. Conclusions: Children are expected to read and listen to complex sentences across the elementary school years. Speech-language pathologists should be aware of the language demands that general education science curricula may pose to students at different ages.