Reported is a study to determine the feasibility of teaching selected concepts related to the particle nature of matter to students in grades 2-6. The lessons developed for this study did not require a high student reading ability, did not require more than one-half hour of time, included the use of analogous mechanical models whenever possible, and emphasized student activities and participation in model building. The opinions of the teachers and students regarding the feasibility of the lessons were ascertained by using questionnaires. Five criteria were established and if satisfied, the concept was considered feasible. Fifty percent of the treatment group would have to answer at least 60% (3 out of 5) of the items on a posttest. The experimental group must score higher than the control group on the posttest and higher on the posttest than on the pretest. The predominant teacher and pupil opinion must be positive. The data related to each of the criteria revealed general satisfaction. Twenty-two of the 25 concepts satisfied four of the five criteria (the level set for feasibility) at all grade levels. A simplex analysis revealed no consistent order among the concepts. It was concluded that it is feasible to teach selected concepts related to the particle nature of matter to children in these elementary grades. (Author/EB)