Constructing Direct Current (DC) electric circuits is simple and engaging for primary students, but that is not all there is to learning about electricity. Mandatory learning in the Australian Curriculum: Science (ACARA, 2018) expects Year 6 students to explain some of the processes underlying electric circuits. The abstract nature of key electricity concepts makes them difficult to teach, especially with primary-age students (Jaakkola, Nurmi & Veermans, 2011; Preston, 2019). Teachers find the concepts challenging to understand making it difficult to introduce the ideas in the classroom. Consequently "teachers might be daunted in teaching the topic through a lack of content knowledge needed to answer off-topic questions" (Chapman, 2014 p. 5). Teacher professional learning in science is an area of critical importance, reflecting national concerns to better engage students with science, technology, engineering and mathematics (STEM) futures (Chubb, 2012). Equipping primary teachers with the skills, knowledge and confidence to teach physics topics like electricity effectively, is an important priority for Australian schools. This paper reports on a two-year project working with teachers as co-researchers that was aimed at supporting primary students' learning about electricity. Vital to the success of this project was the support provided by the researchers, which resulted in improved understanding and confidence in teaching through a constructivist approach.