Here are the fully explained steps for you to download google classroom on your laptop and work on it.
1. You have to use an android emulator on your laptop.
You can use this emulator Smart Gaga
It is easy and smooth to use and you can use it in low specifications also.
2. Install it on your pc
3. Open emulator
4. Now download the google classroom app file on your pc.
You can do it from here: Google classroom
5. Open google classroom apk file with the emulator
6. Now open google classroom on the emulator
And enjoy it just like on your mobile phones