Catastrophic Events
Part III
Lesson 24: Effects of Ash Fall
Focus Question: How does ash affect people and the environment?
Goals:
 Ash and other volcanic materials can erupt into and settle out of the air.
 The size of airborne volcanic materials affects how they move into and
settle out of the air.
 The jet stream can distribute ash globally.
 Volcanic eruptions can create human and environmental risks.
 Ash deposits can create new land.
Teaching Point:
Student Objectives:
 Investigate how volcanic particles, such as ash, erupt into and settle out
of the air.
 Determine how the size of airborne materials affects where and how fast
they settle.
 Draw conclusions about how weather conditions, such as wind, affect the
direction and speed at which ash moves.
 Identify the constructive effects (such as land formation) and destructive
effects (such as on human health and global weather) of ash fall.
 Understand that atmospheric and geologic changes caused by volcanic
eruptions can occur quickly or slowly over geologic time.
Getting Started:
1. Read “Volcano in a Cornfield,” on pages 270-273. It is a true story.
2. In a class discussion, describe how volcanic ash that fell in Paricutin,
Mexico, affected Dionisio Pulido, his farm, and his town. In this lesson,
you will investigate the effects of ash fall.
Inquiry 24.1: Investigating Ash Fall
1. Look at the materials your teacher has set out. How can you use these
materials to investigate ash fall? Discuss your ideas with the class; then
review with your teacher Procedure Steps 8 through 22 in this lesson.
2. Your teacher will give your group one copy of Student Sheet 24.1a:
Investigating Ash Fall-Planning Sheet. What question will your group try
to answer based on the suggested procedures you have just discussed?
Record that question in the first box on Student Sheet 24.1a.
3. Complete the rest of Student Sheet 24.1a by describing the materials and
procedures you will use, how many trials you will conduct, what you will
measure and how you will measure it, and what you will look for.
4. Discuss your group’s plan with your teacher.
5. Discuss with the class how you will record your data and observations and
graph your results.
6. Collect your goggles, dust mask, and plastic box of materials for your
group. You will conduct this investigation outside, if possible. If you have
a clipboard, put your planning sheet on it. Also bring your notebook or a
sheet for recording observations.
7. Review the Safety Tips with your teacher. Then perform your
investigation by following Procedure Steps 8 through 22.
8. Place your construction paper on the ground or work area.
9. Remove the protective paper from the strip of tape. Stick your compass
to the tape, as shown in Figure 24.1. Turn your paper until your compass
matches the direction your group decided on. Record the compass
direction on your observation sheet.
10. Place the small bowl in the center of the tape, as shown in figure 24.2.
The bowl will represent a volcano. Tape your paper to the ground, or
place rocks or other objects on either end of the paper to hold it down in
case the wind blows.
11. Use the planning sheet to decide how much sand you will put into the
bowl each time. Then fill the bowl with this amount of sand. The sand
represents broken pieces of volcanic rock and other large volcanic debris.
12. Designate one student to blow into the tubing. This will force the gases,
ash, and larger particles upward during the model eruption.
13. The person who blows into the tubing should hold it straight and then
place one end of the tubing in the bowl, just touching the surface of the
sample, as shown in Figure 24.3. When your group is ready the student
with the tubing should blow forcefully into it with one quick, sharp blow,
while the other members of the group observe how far the particles travel
and how long they remain in the air. Watch closely. It happens quickly.
14. Draw your results on Student Sheet 24.1b or in your notebook.
15. Use the red pen to mark on the paper where the sand fell. You may want
to write “Sand Trial 1” next to it. Then measure how far from the bowl
the sand traveled in one direction. Record this distance on Student Sheet
24.1b: Investigating Ash Fall-Observation Sheet or in your notebook on a
data table.
16. Refill the bowl with the same amount of sand and repeat Steps 13
through 15. Do this a total of three times. (Do not clean off the sand
between trials. You want it to build up.) Record all other observations,
including wind direction and other weather conditions.
17. Repeat Procedure Steps 13 through 15 using terrarium soil in the bowl.
Remember to use one quick, sharp blow. Conduct three trials, using the
same volume of soil each time. Mark your paper and measure how far
the terrarium soil traveled each time. Record your data and observations.
18. Finally, repeat the steps using cornstarch in the bowl. Use the same
volume each time and measure in the same way each time to keep this a
fair test.
19. The particles from a volcanic eruption are a variety of sizes. Create a
mixture of the three substances by putting equal amounts of each
substance in the bowl. Make a prediction. How will the mixture erupt into
the air and settle out around the volcano? What factors will affect how
and where the substances settle? Discuss your predictions with your
group.
20. Use the tubing to blow the mixture into the air. Discuss your results.
Were your predictions correct? How was this eruption like a real volcanic
ash fall? Add your results to your drawing.
21. Clean up. Throw away the ash fall sheet, plastic tubing, and dust mask.
Keep all extra sand, cornstarch, and terrarium soil in the cups. Place a lid
on each cup. Return materials to the plastic box.
22. Make certain your data and observation table are complete. Then graph
your results.
Reflecting on What You’ve Done:
1. Share your graph with the class.
2. As you analyze the graphed data, consider factors that may have affected
your results. Answer these questions:
a. How did the size of the particles affect how far each substance
traveled?
b. How did wind affect the way in which materials erupted into and
settled out of the air?
c. How did the size of the particles affect how long they remained in
the air?
3. Apply what you observed in the lab to a real eruption of ash and other
volcanic fragments. Answer the following:
a. How might wind or other weather conditions (such as rain) be a
factor in a volcanic eruption?
b. How does hot air behave? Knowing this, why do you think a hot
cloud of ash rises so high in the air?
c. Look at the illustration of the jet stream on page 62 in the reading
selection “Why Does the Wind Blow?” (Lesson 5).If the ash reached
the height of the jet stream, what path might the ash take? How
might this affect weather globally?
d. Look at the illustration of page 31 in the reading selection, “The
Source of the Earth’s Heat.” How might ash clouds affect
temperatures on the earth?
e. If ash repeatedly erupted from a volcano, how might the land
change over time?
4. Watch the video The Eruption of Mount St. Helens with your class.
Discuss the destructive and constructive effects of ash fall with your class.
5. Look ahead to Lesson 25, in which your teacher will assess your
knowledge of volcanoes. To prepare for this assessment, complete
Student 24.1c: Volcanoes Review for homework.