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Whelmer #46: Pretzel Predictions
Description:
Students are challenged to predict how many pretzels they can eat in a
minute.
Science process skills:
- observation
- number relations
- measurement
- space/time relations
- communication
- prediction
Complex reasoning strategies:
- comparison
- induction
- analyzing errors
- problem solving
Standards:
K-4:
- Plan and conduct a simple investigation (Standards A.1.2).
- Employ simple equipment and tools to gather data and extend the senses
(Standards A.1.3).
- Objects have many observable properties (Standards B.1.1).
5-8:
- Identify questions that can be answered through scientific investigations
(Standard A.1.1).
- A substance has characteristic properties all of which are independent
of the amount of the sample (Standard B.1.1).
9-12:
- Design and conduct scientific investigations (Standard A.1.2).
- The physical properties of compounds reflect the nature of the interactions
among its molecules (Standard B.2.4).
Above Standards from the National
Science Education Standards.
Content topics:
- digestion physiology
- absorption
You will need:
- pretzels, bow-tie shaped
- stop watch
Instructions:
The best pretzels for this activity are the large (2" x 3") bow-tie shaped
pretzels sold in bags. There are usually sixty to seventy in a bag.
Students usually make a mess eating the pretzels at a hurried rate. Perform
this activity in an area where the clean up of pretzel crumbs will not be
a major chore. You might want to have drinks available for the participants.
Presentation:
Ask several energetic and vocal students to stand in front of the class.
Ask them to predict how many pretzels they can eat in a minute. Many will
guess twenty or thirty, or even the entire bag!
Write their names on the board. Write the predicted number of pretzels after
each student's name.
Before starting the "contest," give each contestant and audience member
a small (1") piece of pretzel. Ask them to chew it slowly. After that experience,
do the contestants want to change their prediction? [Some will lower their
estimates.] Ask the rest of the class for their opinions about the contestants'
predictions.
Inform the students that certain chemicals are added to pretzels during
the manufacturing process to assure the complete dryness of the interior
of the pretzels. Does that make them want to change their prediction?
For a start, give each contestant five pretzels. Assure them that you have
plenty more. You will give them more as soon as they have the first five
chewed and swallowed.
Start the stop watch and allow the contestants to begin chewing. On a rare
occasion a student will be able to chew and swallow more than five pretzels
in a minute. Most will only be able to swallow two or three. Why? Most students
completely overestimate their ability to eat the pretzels in a minute.
Content:
It requires only a portion of one pretzel to absorb all of the saliva in
a student's mouth.
Predicting is a skill a person needs to develop to become a successful scientist.
Students should notice how predictions change as more information is made
available. The experience with eating a portion of a pretzel and information
given about the additives should have motivated them to change their predictions.
Scientists gather as much information as they can before making predictions.
As new information is made available to them, they often change their predictions.
Assessment:
Type: small group and individual.
Content/Process: prediction.
Age/Level: all.
Using a liter jar or beaker, fill it with peanuts that are still in the
shell. Students are to predict the number of peanuts in the jar. The prediction
process is a multi-stage process. Students should come closer to the correct
number with each step. Assess them based on their ability to revise their
predictions with additional information.
Step 1: Show each group the jar with peanuts and give each person a peanut.
With this information, record Prediction 1.
Step 2: Group the students into groups of 4-5 students. They can use their
peanuts together to revise their predictions. This is Prediction 2. Students
in the same group do not all have to record the same prediction.
Step 3: Give the groups a 20 ml, 50 ml, or 100 ml beaker. Using their peanuts
and these beakers, revise the prediction. Record this as Prediction 3.
Step 4: Allow each group to decide what they would like to do next to enhance
their ability to refine the prediction. Other than counting the peanuts
in the original jar, they can follow their agreed-upon process to refine
their predictions. This is Prediction 4.
Make a chart on the board or overhead on which students should record their
final predictions. Graph the predictions before revealing the actual number.
Discuss the process the groups used to refine their preditions. The graph
should resemble a bell curve with the highest point being the closest to
the actual number of peanuts.
Notes:
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