Switching from PC to Chromebook and back again

My students use Windows PCs for code.org in the classroom. They want to be able to work at home on their Chromebook. We are using CS discoveries with 8th grade students. When they login, they have to rejoin my class. None of their work from the PC is there. What am I doing wrong?

Since they are using a web browser to access Code Studio, they should not have to rejoin your class. Everything they do in class gets saved in their profile. Are they in the correct version of the curriculum when logging in from home? Are they using the same login ID to login from home?