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.