Here are some ideas:
You are stranded on an Island for 3 days, your only resources are those found in the overwhelmingly beautiful landscape.
Your eyes are two different colours, one blue and one green, the green eye sees truth, but the brown eye sees much much more.
You are the most famous 3rd Grader in the world.
Also, the book Writing Magic is lovely for Imaginative or Fantasy essays, stories, and books!
In a situation you are even with one another (money, learning.)
Grammar is how you speak
If we did not have grammar people would always talk in slang or not in complete sentences and it would be hard to understand each other