Begin by asking your child to come up with ideas for surveys. Surveys
can involve asking people questions. They can also involve just making
observations. Surveys are related to chances because they involve
only a sample. You ask a sample of people questions, but you don't
ask all people. Chance comes into play because chances are that a
larger group will give the same answers or results as the small group
sampled. The match between groups is more likely when the sample is
large.
Any survey needs to have a limited number of possible responses.
This is important to keep in mind when coming up with survey questions
and thinking about possible responses. For example, a survey of the
hair color of people walking down the street on a particular day at
a specific time has a limited number of responses: black, brown, blond,
gray, white, red. However, there could be the occasional purple or
green hair. These colors could be put in a category of “other.”
It is best to begin with surveys that have only two possible responses,
like rain and no rain. Chances are easier to calculate that way. Here
are some ideas for survey questions that have just two responses.
Some are to be asked; others can be observed in a public place.
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| Do you like eggplant? (yes, no) |
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| Are you older or younger than 25? (older, younger) |
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| Are people wearing shoes or sandals? (shoes, sandals) |
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| Are people walking to the left or to the right? (left, right) |
As your child gathers data, by either asking people questions or
just watching them in a public place, she needs to keep the data organized.
Making tally marks in two columns is an easy and quick way to do it.
Once your child gathers enough data (and you might want to decide
how much is enough beforehand – 30? 50? 100 people?), chances
can then be calculated.
Calculating the chances can be done by hand or on a calculator
by dividing the number of people who answered each way by the total
number of people. (Remember that a result of 0.125 is the same as
12.5%.) This calculation will give a percent for each answer, and
the two percents should add up to 100% (all the people).
The percent that your child gets as an answer is the percent of
people giving a certain response, but it is also a percent chance
because you can use the data to predict the chance of the next person’s
response. For example, if 28% of the people who passed by are wearing
sandals, then there is a 28% chance that the next person who walks
by will be wearing sandals.
