Yakima WATERS Mini Lesson
Accuracy and Precision Exercise Using Surveying Techniques
Targets and Assessment
WA Science Standards Addressed:
 9-12 INQB Investigate
 9-12 INQC Explain
 9-12 INQF Communicate
Lesson Parameters
Content Area: Interdisciplinary
Overview: In this lesson, students will explore accuracy
and precision by marking landmarks using handheld GPS
receivers and later checking their results with the actual
latitude and longitude.
Grade Level: 9-12
Assessment
 Check to make sure the students’ GPS locations
are close to the actual coordinates of
predetermined sites.
 See rubric for potential grading options
Suggested Time: 2 class periods
Special Materials:
 5-6 handheld GPS receivers
 Computers with access to the internet
 Student worksheet
Learning Outcomes:
Knowledge: Students will be able to correctly apply the terms accuracy and precision when assessing
the results of a GPS study.
Skill: Students will be able to operate GPS receivers, and determine the latitude, longitude, and
elevation for their location.
Science Concept Background:
Precision—The ability of a measurement to be consistently reproduced
Accuracy—The ability of a measurement to match the actual value of the quantity being measured
Many different sciences use Global Positioning System (GPS) data to classify/categorize samples for
experiments. For example, a biologist may use GPS data to determine the migration patterns of Big Horn
Sheep in the Rocky Mountains, or a geologist may use GPS data to establish how much a continent has
shifted due to tectonic processes. In science, precision and accuracy are very important in the validity of
an experiment. Therefore, it is very useful to determine how accurate and precise your GPS receiver is
before gathering important data.
Materials:
5-6 Handheld GPS Receivers
Computers with access to the Internet
Student Worksheet (see attached document)
Procedure:
Accompany the students to the desired location where you want them to take GPS points, and
separate them into groups according to the number of GPS receivers available. Make sure you calibrate the
GPS receivers before hand! See the User’s Manual if you need to. Explain the difference between accuracy
and precision, and how the GPS works. Ask the students to find the latitude, longitude, and elevation of GPS
points at several locations of their own choosing (I chose to use the school’s baseball field). Also, ask the
students to find the latitude and longitude of several pre-planned locations, so that data may be compared
between students and other classes. Allow students to compare data gathered from their GPS receiver, so
they may determine how precise their instruments are (For student direction see the Accuracy Precision
Exercise student handout).
Key Questions:
How much does the information vary from receiver to receiver?
Does the GPS information vary if you stand underneath a tree or other object?
Once back in the classroom, direct the students to the website http://mapper.acme.com/. This site
allows the students to enter their locations from the GPS data they gathered, and determine the accuracy of
their instruments. Ask students to share their results with the class.
Key Questions:
How accurate was your GPS receiver?
Did your accuracy change throughout your data collection?
How might the accuracy of the receiver change throughout the day, as more or less satellites
are available to determine your location?
Extension(s):
It may be a good idea to collect the data from the students after they are done checking the accuracy
of their instruments. You can enter the data from all the groups in each class into an Excel spreadsheet. From
here, you can calculate the standard deviation of the data from the pre-planned sites in order to classify the
precision of the GPS receivers. During the next class period share your data with each class. Explain how
precision and accuracy relate to one another when dealing with a large sample set (i.e. as precision decreases,
accuracy decreases).
Key Questions:
Did accuracy and precision change throughout the day, and if so, why might this be the case?
Based on our results, what would be the best time to gather data?
Teaching Tips:
You may want to beef up on your knowledge of the GPS because students will as questions. If there
are not enough GPS receivers for each students, make sure everyone gets a chance to operate device and read
the location data for their peers to record.
Supplements:
Accuracy Precision Exercise student handout, computers with Internet access
Rubric
Element
Participation
(10%)
Directions &
Prioritizing
(20%)
Excellent
(10 pts.)
Good
(7.5 pts.)
In Development
(5 pts.)
Student fully
participates and
works well as a
group
Student follows
directions
perfectly and is
able to prioritize
time efficiently
Student does their
part in the group
Student does their
part, but does not
work in the group
Student follows
directions well and
is able to finish on
time.
Student finishes on
time, but does not
follow directions.
Need
Improvement
(2.5 pts.)
Student doesn’t
put full potential
into their part of
the group project
Student does not
follow directions
and does not finish
on time.
Not Scorable
(0 pts.)
Student does not
participate in the
investigation
Student does not
follow directions
and does not use
their time well
Knowledge
(50%)
Responsibility
(20%)
Student goes
beyond the
correct answer
and explains
extra ideas and
thoughts
Student is
responsible for
his or her area
and equipment
and others
equipment
Student correctly
answers the
questions given,
understands most
concepts.
Student answers
most questions
correctly but does
not understand
concepts.
Student answers
few questions and
does not
understand
concepts.
Student does not
understand and
does not answer
questions
Student
responsible with
their area and
equipment
Student does not
show
responsibility to
all their equipment
or all their space
Student does the
least work and
shows the least
amount of
responsibility but
still finishes the
project.
Student shows no
responsibility for
actions or
equipment
Author: Christopher Markley, Yakima WATERS Project, CWU, Fall 2009