Observational techniques were employed to gain insights into students' experiences from three perspectives (learner, teacher, and observer) as related to four aspects of a set task (nature of the task, including its purpose; how the task was carried out; perceived significance of outcomes achieved; and significance of outcomes in terms of science learning/teaching). Extracts and examples from 16 lessons (analyzed) in depth) are presented to exemplify aspects of science lessons identified as problems associated with these experiences, and to point to reasons why children do not significantly alter their perceptions about how and why things behave as they do. One group of factors which appeared to lessen the likelihood of students appreciating the significance of a task was an observed tendency on the part of some students to see the task in isolation. Because of this tendency, they failed to set the present experience against other related experiences. In addition, it was found that some students were unable to effect design requirements of a task and ended up carrying out alternative tasks. These and other factors (including those linked to students' cognitive structures) indicate how different students' experiences can be from those intended by teachers and curriculum developers. (JN)