I hate teaching a grammar unit. The idea seems crazy to me - kids hate it, teachers hate it, so why do some of us insist on teaching this way? I think the answer is that we know that kids are struggling with grammar and conventions, and use of technology certainly doesn't seem to be helping things. We feel a responsibility to help our students to be better writers. One idea that you might try instead of those dry worksheets is a grammar journal.
Grammar journals allow students to apply their knowledge of writing in a practical way. The journals are also a safe place where students can take risks, knowing that errors will not hurt their grades. Students are given various journal prompts - anything that you as a teacher would authentically have them write about. These prompts might be related to literature being studied in class, might be based on an issue that is relevant to students, or it might be a free writing activity.
Prior to giving the students their writing prompt, give a mini lesson on the grammar skill that you want them to practice. I would usually pull lessons from trends that I was noticing in their work. If comma splices were showing up in my major writing assignments, I would do a mini lesson on comma splices before introducing my journal prompt. Students would then be told to pay special attention to their use of commas in their writing.
I like to have students write two column journals. On the left hand side, students will write their journal entries. On the right hand side, they will make comments related to the mini lesson. So in this case, students would write about their use of commas. They have the opportunity to reflect on their use of commas, places where they left commas out, and ask questions.
Food for Thought... how do you teach grammar?