2
Reaction Time: “Quick Communication”
GOAL
The goal of this lesson is for students to experience the
body reacting, while also increasing their awareness of
body systems in the context of the scientific method.
Set-up:
-Distance/Time chart
-Rulers (class set)
-Reaction Time poster
-Dry erase marker
-Student Worksheet “Reaction Time Part II”
PROCEDURE
Engage (10 minutes) Introduce Gravity
•
Review the concept of the dropped ruler and the reaction time necessary
to catch the ruler.
•
Student volunteers may read their work from last week.
Explore (10 minutes) Galileo’s Law of Free Fall
•
Ask students, "How can we measure our reaction times?"
•
Ask students, “What do you remember about Galileo's law of free fall?”
(All objects fall at the same speed, in the absence of wind resistance).
•
"What is speed and how do we measure it?"
•
Think of the speed that you drive a car. "What two units of measurement
are used to describe the rate of a moving car?" Speed has two components:
distance and time (miles/hour).
•
Show the students the ruler once again, and ask them, "How can we use
this ruler to measure our reaction time?" Students should recognize that
we have a distance component, but not a time component.
•
Students should hypothesize methods for measuring time. Ideally, one
student will suggest using a stopwatch.
•
Have two student volunteers come to the front of the class. One student
will catch the ruler as the teacher drops it, while the other student measures
the reaction time. This demonstrates that our reaction times are less than
a second, which is too short to be measured with a clock, watch, or
stopwatch.
Grade 4: Reaction Time Unit
UNC-CH Brain Explorers
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