Making meaningful comments on student's work is a time intensive process, I agree. It has been extremely difficult for me to learn how to do this with my math and science students.
Math students are so anxious to simply get the "right" answer and so uninterested in learning how to explain what they know....let alone in writing. I have labored with some success, but much more failure in writing comments that will inspire them to explain more about the steps they used, use a picture to illustrate their thinking or many other things. It is another place where I wish we could have some professional development. I know sometimes I think I should just give up on math journals, but I just can't. I believe in them, I think most of my students would tell you that they've actually been useful and I just hope that I'll get better and better at teaching them how to write in math class.
6th & 7th grade science students struggle with writing about scientific topics. I wish I had a better set of feedback comments to use with them to explain what they know. Again I think it's my lack of understanding how to use writing to it's maximum advantage. I've gotten better with my feedback in that I can tell them they need to write a better sequence of steps, or they need to use evidence to support a conclusion....but I just feel like this falls short.
Another teacher writes about his transformation . It has empowered his students to pause to look at the ideas he has to give on their writing...establishing a learning dialog between the 2 of them. Sometimes I think it is because we are in such a rush, rush cycle of behavior that taking time to teach students to read what we've written and then process what it means for their writing...is just a "drag". It takes time to think, reflect and revise.
I'm not sure where I'm going with all this in my classroom. I think I need to have a better prescription for writing...probably so they have a rock solid idea of what the targets are. But you know there isn't that much out there about how to write well in math and science. I guess that's my cue to fill the void!!!!