Drinking Chai (3 Act Task)

Grade level: 3rd/4th/5th

Content standards3.MD.A.24.NF.B.4.c; 5.NF.B.7.c

Practice standardMP4

**Note: It might be helpful when doing this task to clarify with students the difference between the colloquial use of “cups” (as in something we drink from) vs. what we mean by the unit of “cups”. This task uses the term “glasses” to refer to the object we drink from in an attempt to avoid this confusion.

Act One

What do you notice? What do you wonder?

Focus question: How many glasses of chai will the teapot make? **

**This is the question Act 3 ‘reveals’ but there are other mathematical questions you could ask about this video & answer using information from Act 2.

Estimate. (Too high? Too low?)

Act Two

Part 1: Amount of chai teapot can hold

It’s hard to see exactly how much chai there is, although it is approximately 5 cups and partway between 1000 and 1500 mL. Here are two pictures to use for different units of measurement.

Part 2: Amount of chai one cup can hold

Here, again, are two pictures showing each unit of measurement. Depending on if you want to work with fractions or dividing larger numbers, you could have your students use cups, ounces, quarts, milliliters, liters…or let them choose!

Act Three

Here is the rest of the video…

And here is the video in its entirety.

Based on the information given, most students would likely calculate that the teapot can fill 10 glasses fully. In the video, only 9 and a half (ish) glasses are filled. Why might this be? Students could have a discussion about how the chai was spilling between glasses or that not all glasses were filled the exact same amount. Would this always be the case? Is there a way they could account for these “real life issues” and make their models more accurate?

Extension

There are interesting ways to extend this problem. Here’s one idea:

  • There are 6 people drinking the chai and they all want to have the same amount. How could we share the chai equally? How many glasses would each person get?
    • What if 6 people are sharing the chai, but one person only wants one cup? How many cups would each of the other 5 people get? Without calculating, will it be more or less than the answer above?

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