Google Classroom

I have known about Google Classroom (GC) since its inception but started to play around with it in January this year. And when I said "play around", I meant exactly that. But now, with the implementation of Movement Control Order (MCO), I had to seriously learn everything there is to know about GC. Creating a lesson session and uploading materials are quite easy. It's just I do not really know if I am supposed to grade my students' works online or offline. At this moment, I am still trying to learn every part of GC but sometimes, I had to go through the tutorials more than once. Plus, half of my students are still giving the same excuses; no internet connection or not compatible with their mobile phones. I am thinking if they can play online games often, doesn't that mean that they have internet connection?! They need to find a better excuse.