Cassie was sitting in the living room of her grandmother’s apartment. Her grandmother had gone out and Cassie was waiting for her friends to come over. The doorbell rang and she jumped up to open the door for Tiana and Huang.
Cassie: Thanks for coming. I forgot my grandma’s birthday is tomorrow. I want to bake her a cake as a surprise. She’s out for a few hours so we have to work quickly.
Huang: Good thing you called us. I remember the last time you tried to bake a cake. It was awful. Please tell me you have a recipe this time.
Tiana: Give her a break. I’m sure she just needs a little help. Let’s go to the kitchen. What’s in the recipe?
Cassie: We need flour, sugar, and baking soda. Grandma keeps baking supplies on the third shelf. Huang, can you hand me the right ingredients?
Huang: There are just a bunch of plastic containers and the labels are definitely not in English!
Cassie: Grandma usually speaks Russian. That must be what’s on the labels. We’ll just have to figure out which container holds which ingredient.
Tiana: How do we do that? What if we mess up? Cassie, you can’t even bake a cake when you know what’s what!
Huang: Come on. Let’s open all of them. I bet we can figure it out.
He took the containers off the shelf, put them on the counter, and opened each one. Tiana took two containers and carefully compared them.
Tiana: This is not going to work. The containers each have a white powder in them. Flour is white and so are baking soda and sugar. Now what?
Cassie: Well, sugar should feel different from flour. Let’s see if we can at least figure out which is sugar.
Huang thought this would be a good qualitative observation. Cassie put her hand in the first container and the substance felt rough. In contrast, the powder in the second container felt smooth.
Cassie: I bet the first container is sugar.
Tiana: How can you know? You only tried two containers. What about the others?
Huang agreed that Cassie shouldn’t make an inference about the containers until she had tried all of them. Cassie touched the powders in each container. Only one felt grainy.
Cassie: The first container is definitely sugar.
Tiana: Three containers to go! What now?
Cassie: Grandma said we were running out of baking soda. Let’s look at how much is in each container.
Tiana looked in the three remaining containers. She noticed that the middle container was filled only halfway. Tiana decided the half empty container was baking soda.
Tiana: So which of the containers left is flour?
Huang: What if we tasted them?
Cassie: NO! NO! NO! My grandma told me once that she sometimes keeps rat poison in the pantry. Don’t taste anything!
Tiana: GROSS! I don’t want to eat rat poison.
Huang: We’ve figured out two containers. There must be other ways we can figure out the last two. Let me think for a few minutes.
Cassie: Think fast because my grandma will be home in two hours!