Looking at slang terms can also be helpful in teaching connotation and denotation. "Cool", "hot", "awesome", "sucks", or even "bees knees" can each be used to show how phrases take on multiple meanings.
I find that the best way to teach denotation and connotation is to use emotionally charged words. My favorite example is fat or skinny. The kids can really relate to those! I have my students give the reactions that a person would have to each in these contexts.
This is a fat hot dog! (Usually this would mean a good hot dog)
Oh no, this dress makes me look fat. (Not a good thing!)
Skinny is even better. Some people think skinny is a good thing, and some people think it’s an insult.
I want to look skinny for my wedding!
I don’t want any skinny kids on the team!
Since context is the key to denotation and connotation, I often have them draw the word in two contexts. They write the dictionary definition (I tell them to remember d for dictionary, d for denotation) at the top, and then draw two scenarios. For one, the word has a positive connotation, and for the other it has a negative one. Then send them looking for other words with different denotation and connotation.
There are also activities in the documents section here at enotes.