making it fun
I have taught 6th grade LA for 10 years and have striven to make it as fun and stimulating as possible. I'm sure fun ideas will come to you with experience. I sometimes use funny worksheets published by Scholastic or Hot Fudge Monday. These practice sheets are a lot more fun than the dry ones you probably got with your textbook. Scholastic even has puzzle-style worksheets with mazes and such. If your school subscribes to Mailbox, this magazine has the occasional appropriate and fun activity for grammar (and lots of other subjects), but it is geared more to the elementary grades (4-5). I wish they had a middle school edition.
You can have the students draw the scene of a prepositional phrase and write the phrase on a sentence strip. You can have the kids write adjectives along with the comparative and superlative forms as mini-posters, post them in the hall and have people vote on their favorite, most unique adjective set.
I also use a computer program called Orchard. It is basically drill and kill but the kids enjoy it because it's on the computer. My kids take turns almost daily with this program working their way through the parts of speech or grammar problems.
About 10 years ago rockers and hip hop artists rerecorded a collection of Schoolhouse Rock songs and I use the "Mr. Morton" cut every year. It is a rap about subject and predicate. My kids always request this song! I have a preposition song too which you can find on the internet. It's just a collection of prepositions sung to the tune of Yankee Doodle.
If you can get some whiteboard slates and dry erase markers, kids will enjoy using them. I use them for DOL and occasionally (dare I admit it?) DIAGRAMMING!!! It may not be the be-all-end-all grammar practice, but diagramming appeals to a lot of kids. It is like a puzzle. It is like a graphic organizer. At the sixth grade level, I wouldn't get too elaborate, but the basic subject-verb-direct object plus modifiers is pretty easy for kids to comprehend. I project simple sentences and have the kids form groups of 2-3. The groups compete to correctly diagram the sentence on the whiteboard slates.