The objective of the current study was to identify an effective learning environment for kindergarten students as they acquire an initial understanding of scientific inquiry activities (SIA) and a simple (idealized) scientific inquiry cycle (SIC). The study aimed to examine (a) the effects of instructional support and (b) the role of similarity across scientific phenomena illustrating the SIA/SIC in helping children acquire an initial understanding. The study used a randomized group treatment design with children aged 5-6 years (N = 231). Similarity of scientific phenomena and specificity of instructional support related to the SIA/SIC were systematically varied across conditions. Results indicated that SIA/SIC-specific instructional support provided short-term benefits to children's knowledge about SIA and the SIC. In addition, results suggested that similarity of scientific phenomena interacted differentially with children's prior knowledge. More knowledgeable students benefited from variation in their understanding of the SIA/SIC, while similarity helped less knowledgeable children improve their content knowledge.