Give the following problem to your students:

You have a mystery to solve! There are 3 containers on the desk. Each one is MISLABELED, but there is one container with each substance. You have one piece of blue litmus paper, which turns pink in acids or stays blue in bases or neutral solutions. How can you correctly label each container using just one dip? Write a brief sequence of steps that will solve this problem. You can actually have the students DO this exercise using white vinegar for acid, water for neutral, and ammonia for base.