It's
About Time
(Measuring and Describing Amounts of Time)
Background--Measurement
When you measure the length of an object, you usually use a ruler and
make your measurements in units such as inches or centimeters. And when
you measure the weight of something, you usually do it with a scale,
making measurements in units of grams or ounces.
But
without even thinking of it, we also measure time. In this age of computers,
and iPods, cell phones and satellites, tracking time is almost unconscious
for us. But every time someone asks "when is recess?", "how
long before the bell?" or "What time is it?", we are
being asked for a measurement of time. You might look at your watch
and declare "it's 11:15 A.M.". And when you do that, you're
actually declaring a measurement of time. You're telling the person
how much time has passed since midnight, the end of the prior day. And
of course, you are expressing it units of hours and minutes.
We
all use different devices to measure time, and we express it in different
units. Can you list all of the ways in which we measure time? The examples
are endless.
Overview
Students explore the concept of time and specifically how we measure
it, and how we express the amount we have measured.
Exploration
Use the following activities to engage the students in time measurements
and amounts.
A)
Use the chart below to engage students in exploring how they measure
time and express amounts of time. Have them answer each question by
identifying what time measuring device or observation, and what unit
of time they would use to answer the question.
Question |
Measuring
Device or Observation |
Unit(s)
of Time |
Example:How
long ago did Dinosaurs last live on Earth? |
Calendar |
Centuries/
Years |
How
old are you? |
|
|
The
full moon is beautiful tonight. How long until it will be full again? |
|
|
What
was your local photoperiod Monday? |
|
|
How
long is your school day? |
|
|
How
long will it take to boil water on the stove? |
|
|
How
long will it take that speeding car to travel ¼ mile? |
|
|
How
long is the "blink an eye"? |
|
|
B) Have students review the NIST resource "A
Walk Through Time: The Evolution of Time Measurement Through the Ages"
Ask
students to discuss how people measured and tracked time before the
invention of clocks, and before we were distracted by street lights,
television, cell phones etc. What devices did they use? Or what observations
did they make? What units of time were most important for them to keep
track of then?
National
Math Standards