The other day a student asked which "shit" we were going over.
Recognizing this as a chance to review some minimal pairs (and correct an embarrassing mistake) I said, "We are going over the homework shEEt, remember that shit means something else." I grabbed my marker as some students laughed and explained what shit meant to those who didn't get it.
Then I made my way over to the board, "It's like ship or sheep"
Then I draw the beautiful sheep, to which one student says, "Sheep means like cloudy?"
Everyone laughs at my sheep as I try to defend it, "It isn't a cloud it has a head...and legs"
To which the student replied, "I thought it was raining"
At this point I just have to conceed my art is not the best. "Fine. OK. I am no artist, but just remember a shIp is not shEEp and a shIt is NOT a shEEt."
There is lots of stuff online to help you help your class with minimal pairs. When we studied minimal pairs earlier to help with the TOEFL. We used this worksheet which worked well.
ESL handouts also offers a worksheet which makes students listen carefully to George Michael's, "Careless Whispers"
If your students still struggle with minimal pairs there are lots of fun activities to do in class. My favorite website for home study is: http://www.shiporsheep.com/
If you prefer books then you're lucky. When I took my CELTA and were my go to books for minimal pair and overall pronunciation help!