With ongoing calls to engage students in science through physics lab instruction, understanding how students frame lab environments informs instructional approaches that promote students’ productive engagement. To deliberately identify students’ frames in a new lab environment, two students who were previously in experimentation physics labs were placed together during the first activity of a content-reinforcement lab. The students initially framed the activity as exploring the phenomena and developing investigations, similar to the previous semester. However, their frames rapidly shifted to filling out a worksheet as they watched their peers finishing the lab. These results demonstrate the speed at which students’ frames can dramatically shift as they enter a new lab environment. As goals for lab instruction transition, attending to students frames throughout their undergraduate lab experiences will be vital for promoting positive learning experiences. © 2020, American Association of Physics Teachers. All rights reserved.