As a classroom teacher with my gifted certification, I always ended up with more than my share gifted students. I remember my last year in the regular classroom I had 6-7 gifted students who left for over an hour three times per week during language arts. It was so stressful at first thinking about how I was going to meet the needs of those students! They were missing a lot of instructional time, not to mention time for practice and reading. After some work, I developed a great plan for them. I let them do their own literature circle. If you haven't used literature circles, think of them as a great way to get kids excited about reading! They are like a book club for kids, but with a little more structure. There are tons of websites and books about literature circles, and many different ways to run them. I tried many different things over the years, but in the end I fine tuned my methods. I gave each student a laminated file folder with their "role" on the cover. They completed their role and made notes on it, and kept the notes inside the folder. The notes from that role stayed with that folder, and the folder was passed around.
With my gifted students, I chose a book that was on their level. I started out assigning them roles, and they kept their role for a week. Then, they rotated within the group. As a group, they chose how much of their book to read before the next meeting. Since they were gone for most of language arts, they were to read and complete their literature circle job on their own time before their group meeting. This worked great, since gifted students often finish their regular classwork before everyone else. If they finished their math, social studies, or science early, they could use the extra time to work on their literature circle work. It was great, because I wasn't constantly worrying about them getting bored waiting for the other students to finish. I felt like they had productive work to do throughout the day, instead of just giving them busy work.
When the gifted students returned from their gifted class, they used the time that was left in language arts to discuss their reading from that week, and their role. I left them to discuss the book on their own, and some days I would drop in on their group to eavesdrop on their discussion. In addition, this group turned in the write-up of their role each day so that I could be sure that they were completing their work, and understanding the book. It worked great! They were able to take a lot of ownership over their learning, and I felt like they were getting what they needed in language arts.
Of course, that is just one example. There are lots of great ways to differentiate! I hope to post more in the future. In the meantime, feel free to use your gifted teacher as an excellent resource. She or he can help you with suggestions and/or ideas for your individual students. Look for ways that you can let the students work independently, with some supervision from you. This will allow those students to use their gifted-ness as an asset to their learning instead of a burden that causes them to miss out on class time.