Monday, December 20, 2010

Measurement: How Many Licks Does it Take?

Remember the old Tootsie Roll Pop commercial...



This lab addresses that very important question, How Many Licks Does it Take to Get to the Center of a Tootsie Roll Pop? 

There are quite a few scientific skills that go with this lab...
...scientific method
...measuring mass
...collecting data
...graphing data
...extrapolating based on data gathered

For today, we'll focus on the first three things listed.  We'll come back to the graphing and extrapolating next week.

Before we begin, there are a few assumptions being made in this lab
  1. The center of the pop is the stick.
  2. The pop is made of a uniform material.
Question:
How many licks does it take to get to the center of a Tootsie Roll Pop?

Hypothesis:
If I lick the pop _____ times, then I will reach the center.

Procedure:
  1. Measure the mass of the pop and wrapper.  Record.
  2. Lick the pop 10 times.
  3. Measure the mass of the pop and wrapper.  Record.
  4. Repeat steps 2 and 3 five more times (or as many as class time allows). 
  5. Finish the pop.
  6. Measure the mass of the stick and wrapper.  Record.
Graph the data.
You can have the students graph the data by hand and then draw in a best fit line to determine how many licks it would take.  Or you could have the students use Excel to graph the data. 

Teacher Notes:
**Make sure you define a lick before you start.  They can't be "dainty" or they'll never gather enough data and their graph will be unusable.  Define a lick as putting the pop in their mouth, twirl it around once and removing it. 


Tune back in next Monday for step-by-step instructions for creating graph (including the best fit line/trend line) in Excel. 

I know, you aren't sure you can wait a whole week for such exciting information.  Try to contain yourself.  And, while you're waiting, go find yourself a Tootsie Roll pop and start licking... :)

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