Ideas Please! I need to teach a compare/contrast kindergarten lesson plan for a job interview.?

I had a job interview today for one of two kindergarten long term substitute positions. They told me during the interview that they were going to pick the top 2 or 3 candidates to perform a lesson plan and then they would make their decision on the final 2 teachers to hire. Anyway, I did get a call back from the school secretary this afternoon, and she said on Monday I have to perform a 15 minute lesson on comparing and contrasting geared toward kindergarteners. That's all the information she had. So I have just this weekend to develop a lesson plan, tweak it to 15 minutes, make sure it is based on compare/contrast, and is geared toward the kindergarten grade. (I should also mention that this is for an urban school with many kids coming from different backgrounds and poverty). I would really appreciate any advice, ideas, and suggestions! Thank you!