Apparently my comparison of symbiotic relationship types using the Kardashian clan as example organisms was too abstract for the middle school.
Parasitsim = Kourtney and Scott (one is harmed, one benefits)
Mutualism = Kourtney and Khloe at Dash (both benefit)
Commensalism = Bruce Jenner and/or Rob and the "girls" (one doesn't notice, other benefits)
Ok. I also thought it would be funny to start the lesson reading the learning objective. "Today's lesson is on relationships" then said "... I do wish I had that lesson in 8th grade."
There was that weird class pause thing that doesn't happen that often but happens enough to have a "the thing the teacher just said was weird" vibe.
So I moved onto the regular science bit.
Parasitism = gross tape worms
Mutualism = Flowers and bees
Commensalism = the Barnacle on Whale
"I suppose you could never prove to the mind of the most ingenious mollusk that such a creature as a whale was possible." -- Emerson