Here are two ideas - one with the free resources and one subscription-based:
Review the string instruments and especially emphasize the cello. Listen to a recording of Yo-Yo Ma performing (my favorite recording is Yo-Yo Ma and Emanuel Ax "Brahms Cello Sonatas"). Then watch the BrainPop movie. Use the "Activity," "Graphic Organizer," and/or "Vocabulary" sheets to fuel group discussion. If you have an interactive whiteboard, I would recommend just completing them as a class on the board rather than making copies and wasting time passing out materials. If you have short class periods like me, I try to avoid those activities when I can. [Extension: Watch a YouTube video of Yo-Yo Ma performing live. Or do a movement activity to one of the Brahms Cello Sonatas, showing the form of the music]
Watch movie. Use the "Talk About It" and "Activity Worksheets" to reinforce skills. Or download my homemade worksheet that I used with my students here (it incorporates some of the worksheets from BrainPopJr with my own homemade stuff). [Extension: Use any of the drill worksheets at SheetMusic1 - they have a huge library of free downloadable stuff, great resource!!)
It is my personal belief that these little movies are so fun, catchy, and entertaining that they can actually "teach" better than me at times - especially when you are a verbose, long-winded teacher and you only have 50 minutes per class period!!!