A Batty Mapping Activity: A Study of Echolocation
Related National Standards
Tools and Materials Needed
Estimated Time to Complete Lesson
Helpful Web Sites
Students will find how bats use echolocation to find their prey by
using echoes to map the direction and distance to various echo sources
in their surroundings. Science skills are used in the collection of
data as echoes are timed and math skills used to calculate the distance
to the echo sources. Geography is used in the construction of the map
of the area and math skills are used for a scale drawing.
By the end of this activity, students will:
- Determine the minimum distance at which an echo can be heard.
- Determine the distance to a distant echo source by using reflected
- Draw an area map with echo sources and approximate distance located.
- Explain how bats find prey at night without the use of eyesight.
National Standards from the McRel Standards Database
- Knows that an organism's patterns of behavior are related to the
nature of that organism's environment (e.g., kinds and numbers of other
organisms present, availability of food and resources, physical characteristics
of the environment).
- Knows ways in which species interact and depend on one another in
an ecosystem (e.g., producer/consumer, predator/prey, parasite/host,
relationships that are mutually beneficial or competitive).
- Knows that vibrations (e.g., sounds, earthquakes) move at different
speeds in different materials, have different wavelengths, and set up
wave-like disturbances that spread away from the source.
Tools and Materials Needed
- Copy of the program "Borneo: Island in the Clouds."
- Stop watches (1 for each student is ideal).
- Sharp noise source (whistle or firecracker).
- Tape measure (100 foot) or meter sticks.
Estimated Time to Complete
Approximately one week. One class period to watch the video. One class
period to discuss the concepts and to use the bat resources on the Internet.
One period to determine the distance for echoes, and draw a rough area
map and determine the speed of sound. One period to take area echo readings
and determine the distance to echo sources and apply to the map.
Background Information: Bats are a paradox that inspires both fascination
and revulsion. Depending on the culture, they are seen as either a symbol
of good luck or of evil. However, bats have been found to be of great
importance to the ecology of an area as they consume huge swarms of
damaging insects and pollinate trees and plants. In Borneo, the bats
leaving the cave consume over 6 tons of insects each night.
Bats are not the blind creatures of myth. However, they are night feeders
and rely on echolocation to find their prey. Each bat sends out a series
high-pitched cries that reflect from the bodies of the insects and gives
the bat an idea of the distance and direction to that insect. Using
a series of cries, the bat is able to hone in on the prey in pitch-black
conditions and avoid running into obstacles. The police use a similar
technique when identifying speeding cars with a radar gun.
Students can use echoes from a sharp, short sound to identify the distance
to stationary objects outside of the school building. While the best
results are obtained by using firecrackers, acceptable results may be
obtained with short blasts from a police whistle. Be sure to check regulations
in your area.
Sound travels approximately 340 meters/sec (1100 ft/sec). If a sound
produces an echo in 4 seconds, the object producing the echo would be
half that distance away (the sound takes half the time to get to the
object and half the time to return). The distance for an object with
a 4-second echo return would be 2 sec X 340 meters/sec or 680 meters
(2200 feet). By applying the distance found to a sketch of the area,
students can identify the distance to various suspected echo sources
and build a scale map. The distance allows students to discriminate
between possible sources and to eliminate other possibilities. The direction
to the objects is usually estimated but could be determined with a compass
if more accuracy is desired.
18:40-22:15 Segment describing the bats and how they prepare for hunting
for insects. Make special mention of the bat ears shown about 20 seconds
after the segment begins.
- Watch the "Living Edens: Borneo" video. Discuss the food sources for
a number of the animals. Note that some eat only vegetation, others
eat only other animals and still others will eat both. Discuss the bat
flight and the search for insects. An example of bat sounds can be found
on the Bat
Conservation International site.
- Take students to an outside area with a flat wall. Have students
line up about five feet from the wall and have one student in the middle
clap once loudly. Ask students if they could hear an echo from the wall
(the answer will be no). Back up from the wall in several meter intervals
until an echo is heard by a majority of students. Reposition the line
until the class determines the approximate distance at which an echo
can first be heard. The distance will be about 17 meters or 50 feet.
By dividing the distance to the wall by the speed of sound, it is found
that a human must have a delay of about .1 seconds to hear an echo.
Bats are much better than this.
- Have from a point in the center of the area to be mapped, have students
draw a rough sketch of the area with buildings and other large, flat
objects that may be echo sources identified.
- Have the students take the timing devices and tell them to click
the watch on when they first hear the sound and click it off when they
hear an echo. The person making the sound should do a countdown to when
they will make the sound. Students should collect a fairly large number
of times, about 40 or 50.
- Place the numbers in order from smallest to largest and a pattern
should occur that identifies echo sources. If the groupings are hard
to identify, take more readings. Some of the values will not fall in
the groupings and may be discarded as inaccurate readings.
- Students should average the groupings and determine an average time
of echo for each of the echo sources. By taking the value, dividing
by 2 and multiplying by the speed of sound, the distance to each source
may be found.
- Apply the distances to the sketch maps of the area. The maps may
be redrawn on graph paper using a standard scale.
- Apply the activity to bats and the use of echolocation.
Helpful Web Sites
Bat Conservation International
Bat Conservation International is an organization that promotes understanding
of bats. This site has bat information, a place to ask questions, samples
of bat sounds and more.
Bat Links Page
This is probably the most extensive list of bat links on the entire
Internet. There is information on bats, hat houses, bat house temperatures,
school sites, information site and educational activities.
"How Stuff Works:
Radar and Echoes"
"How Stuff Works" is a large site that explains how many common things
work. This is the section on radar and echoes.
National Federation of the Blind
This is the NFB resource page for kids. It has general information on blindness,
information about the causes and treatment, and links to companies and
Students may be assessed through their participation in the class discussions.
Calculations may be graded for correctness. The map would be assessed
by evidence of student application of the calculation results to the
finished map. Depending on the age of the student, the map may be drawn
- The local police department can be used as an outside source to
come and discuss both traffic safety and the use of radar to identify
the speed of cars. Most police departments will provide a demonstration
and will use hand-held radar devices to determine the distances to objects
that the children identified in their echo experiment.
- Students may investigate how the blind are able to navigate in their
surrounding by the use of a cane. The cane is used both to find objects
by touch and to allow the detection of more distant objects by echoes.