This narrative account describes issues confronted by third grade students, their teacher candidates, and their experienced teacher as they sought to implement a knowledge building approach. Data come from the class database, videotape recordings, and the teacher's narrative account of the year. There is particular emphasis on the teacher's experience with change and the difficulties she encountered related to: changes in teaching style (using the Knowledge Forum database in a way that fit with her previous practice while simultaneously improving it); changes in approaches to students' misconceptions (tensions between the teacher's need for students to state, confront, and move on from misconceptions and her ability to hold back or provide appropriate information at key times); and changes in writing instruction (practical concerns related to the shift from children's writing and authorship as primarily an independent activity to a model of writing through Knowledge Forum, in which authorship and ideas are shared). The teacher's concerns about the type, quality, and volume of writing done by students are examined, comparing them to previous approaches to writing instruction. Appended are images and text representing structures: Math Science Investigations (MSI), The Ontario Science Curriculum, the children's responses and the children's diagrammed structures in the database. (Contains 15 references.) (SM)