We examine (a) the development of 3 student learning practices (SLPs)--listening, speaking publicly, and making and using records--that are central to participation and engagement in academically ambitious classrooms and (b) the teacher's work supporting the enactment of the SLPs in the context of a summer mathematics laboratory. We identify assets that the students brought to their work--assets that can remain invisible and underused in modal classrooms--as well as the work the teacher did to support these SLPs through cueing, modeling, scaffolding, providing feedback, and defining the practice. We found that as the teacher taught these SLPs, she attended to individual student understandings, grounded the work in the subject-matter domain, and was equitable and ambitious in her instruction. Situated in practice, this analysis enriches the literature on SLPs and helps educators see the more complicated forms that participation and engagement can take in classrooms.