Yakima WATERS Mini Lesson
Avalanches!
Targets and Assessment
WA Science Standards Addressed:
 6-8 INQE —Model
 6-8 INQF —Explain
Assessments:
 Student learning will be evaluated by comparing
their pre-assessment explanation of an avalanche
with their response to question number 5.
Student participation and effort will be evaluated
based on the completion and detail of their data
table completed and responses to questions 1-4.
Lesson Parameters
Content Area: Physics, Weather/Climate, Earth Science
Overview: Students will create and observe avalanches using models
made of readily available materials. Students will learn about
avalanche science and what it means to them in their locale from a
powerpoint presentation.
Grade Level: 6-8
Suggested Time: 1 hour
Special Materials:
 Poster board, Flour, Sugar, Potato Flakes, Stones,
Cheesecloth
Learning Outcomes:
Knowledge: Students will be able to define avalanche and explain how an avalanche is triggered.
Skill: Students will be able to identify layers in the model as strong or weak layers based on their observations
of the avalanche. Students will be able to relate the materials in the model’s snow to real types of snow
crystals. Students will be able to predict what type of slopes avalanches occur on.
Disposition: Students will increase their awareness of the dangers of avalanche hazards.
Science Concept Background:
Avalanches occur when deep snowpack builds up on steep terrain over a season. In each snow event, a new
layer of snowpack is added and is characterized by snow crystal size and shape, snow water equivalent (how
wet the snow is), and depth of the snow layer. Sometimes these layers bond really well to each other,
sometimes they do not. Weak layers in the snowpack may characterized by slipperiness, or ball shaped
crystals, low snow water equivalency, low density or thinness of layer. Temperatures and the weight of above
snow layers, constantly are altering the snowpack. As the snowpack becomes heavier, or a forcing trigger such
as strong wind, heavy snowfall, a snowmobile’s weight or avalanche blast (used by ski patrollers) forces a
weak layer to collapse, and a strong layer above it to slide downhill. As the avalanche tumbles down the slope,
it picks up speed, heats up and then quickly freezes into hard/icy snow chunks at its terminus.
Materials:
o Photos or powerpoint of avalanche photos
o 5 lbs of Flour (2 cups/group)
o 5 lb of Sugar (2 cups/group)
o Foam Poster board ~ 15”x20” (1 per group)
o Newspaper
o Measuring cups (1 per group)
o Small Stones
o Cheesecloth
o Protractors (1 per group)
Procedure:
Preparation: To save class time, it is recommended to prepare the models in the foam board for the model
ahead of time. To do this divide each board into 3 sections. In the left section, keep free of added materials. In
the middle section, apply cheesecloth (glue it on). In the right section, glue on several small stones (scattered
about).
Engage students in wanting learn more about avalanches by reading a true and shocking story of a (local if
possible) avalanche event to the class. Then, as a pre-assessment, ask students to write their definition of an
avalanche in their science notebook and what they think causes an avalanche to occur. They should do this
independently. After giving them ample time to complete their responses, have the students share their
definitions and ideas of causes to the class. Write the causes of an avalanche on the board as they share.
Show the students several photos of avalanches in a powerpoint slideshow or with photos. The presentation
should illustrate different types of snow crystals and how snow layers build up over a season.
Key questions:
What kind of slopes do these avalanches occur on?
Are their trees on these slopes?
Which type of crystal do you think would represent a weak layer, meaning it easily falls apart. Which
layer do you think represents a strong layer (think about packing a snowball or building a snow fort!)
What angle of slope do you think is most likely to have an avalanche?
Tell students that they build a model avalanche following the provided instructions and materials in their small
groups. First they will build a snowpack, then they will increase the slope until an avalanche occurs. Handout
student instructions and worksheets for recording observations and reflecting on what they observed.
Extension(s):
Have students answer the reflective questions on the worksheet based on their observations.
Teaching Tips:
You can have students build their models, but this takes more time. Students may need to be refreshed (or
taught) how to use a protractor. Try substituting other materials to see how avalanche develops. Have models
set to fall in the middle of table and away from edge for easier cleanup. Use the waste “snow” material to
create crafts, by adding water and baking. Try to have students relate to their personal experiences with snow
– making snowballs/forts, hearing avalanche guns go off at the ski area, not being able to go to Seattle
because Snoqualmie Pass is closed.
Supplements:
Nova Teachers Avalanche! Lesson Plan:
http://www.pbs.org/teachers/activities/2418_avalanch.html#materials
How do Avalanches Form (video, 4 min long)
http://www.teachersdomain.org/resource/ess05.sci.ess.watcyc.avalanche
Avalanche Dogs!
Local ski areas often have avalanche rescue dog programs. Invite one to come in to the classroom.
See http://drizzle.com/~danc/avalanche.html
Author: Jamie Sheahan, Yakima WATERS Project, CWU, Fall 2010
Sliding Snow Student Instructions
In your groups, you will build a model avalanche following the provided instructions and materials in their
small groups. First they will build a snowpack, then you will increase the slope until an avalanche occurs.
Make sure to complete your data table and answer your reflection questions!
Build the snowpack
1. Spread newspapers on table under the foam board model. Lay the foam board model flat on the
table.
2. Shake out 1 cup of sugar over the entire model surface. This represents the first snowfall of the
season.
3. A big snowstorm comes in, and wind blows the snow all over causing it to be very tightly packed.
Shake out 2 cups of flour over the 1st layer. Pack it down.
4. A few weeks go by without any snowfall (what kind of air pressure is here?). Then we get a light
sprinkle of big fluffy snowflakes. Sprinkle ½ cup of mashed potato flakes over your model.
5. Its February now, we get another huge dump of snow for several days in a row. Shake out 2 cups
of flour over your model and again, pat it down to even out the surface (like the wind).
Increase the slope
1. Have one person hold the protractor against the side of the bottom of the slope (you decide which
will be bottom).
2. Have one person very slowly raise the top of the model to create a slope, while all the other team
members closely observe the snowpack on the slope. Pay attention to any changes that start to
occur as the slope is raised.
3. When a layer in the snowpack “fails”, observe and record what layer failed and the slope angle,
using the protractor that it failed at.
Reflection
Complete your responses to the reflective questions on the worksheet based on your observations.
Sliding Snow Worksheet
Observations
Surface of
slope (from top
to bottom)
Snowpack
layer
Substance
(flour)
Angle (degree)
which it slid
Description of Avalanche
Why do you think it slid?
Reflection Questions
1. What is the range of angles that your snowpack layers slid? In nature, why would a 20 degree slope
not slide? Why would a 60 degree slope not slide?
2. Did the surface type change when/how and avalanche developed? Which surface produced the
avalanche first and why do you think this is so?
3. Did all of the layers slide at the same time? If more than one slid at a time, the lowest one was
probably the weakest layer in the snowpack. Which substance represented the weakest layer and why
do you think it was weaker than the above layers and gave way?
4. What information would an avalanche forecaster need to predict the chance that an avalanche will
occur?
5. Based on your observations and your knowledge in weather and science, explain how in nature slope,
terrain (surface), and different snow types, affect avalanche occurrence.