In this study of fifth-grade students, we examined the relationships and development of communities of concepts related to heat and convection. The study involved five classes of fifth-grade students who worked with a partner for a series of heat and convection laboratory investigations. Students' knowledge was assessed before and after instruction through the use of a written test, concept maps, card sort tasks, and interviews. During instruction each dyad was audiorecorded and observed by a field researcher. The patterns and connections among students' conceptual ecologies related to heat and convection as well as the types of schemas that were accessed preceding and subsequent to instruction are described. The types of knowledge elicited by each type of assessment are identified. Findings include the influence of familial and cultural experiences (such as airplanes, weather patterns, and religious beliefs) on conceptual development, as well as the extent to which competing phenomena (evaporation and dissolving) have on the development of new conceptual understandings. The study also found that each assessment measure elicited different types of knowledge. Concept maps were effective in describing students' existing schemas related to heat prior to instruction. Multidimensional scaling and the card sorting task provided information on students' conceptual organization for clusters of concepts. The interviews and dyad discourse transcripts were most effective in revealing the processes and prior knowledge that students used as they interpreted new observations in light of preexisting experiences.