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Reading passage Grade 6 English Language Arts

Measuring Snow at Winnock Pass: A Grade 6 Reading Passage

A grade 6 reading passage following a fictional snow surveyor who weighs mountain snow to predict how much water a town's river will carry the following summer.

Objectives

  1. Students will cite details explaining how a snow surveyor measures snow and why the weight matters more than the depth.
  2. Students will explain how a mountain snowpack acts as a natural reservoir for a town downstream.
  3. Students will infer what a low snowpack in March means for a town in August.

Vocabulary

Snowpack
The snow that piles up in the mountains over the winter. As it melts in spring and summer, it acts like a giant water tank feeding rivers and reservoirs.
Watershed
A watershed is all the land where rain that falls will drain to the same stream, river, or lake. Everyone lives in a watershed, no matter how far from the water they live.
Reservoir
A human-made lake, usually created by a dam, that stores water for later. Reservoirs supply cities and farms and help control floods.

Also: snow course, snow water equivalent, runoff

Teacher overview

Water cycle instruction often ends at the diagram, while the work of measuring any one stage of the cycle rarely appears. This passage follows a snow surveyor at a fictional mountain pass who weighs snow in March to tell a town downstream how much water its river will carry in August. It also gives students a case in which the easier measurement is the less useful one, because the depth of the snow matters far less than what the snow weighs.

Measuring Snow at Winnock Pass: A Grade 6 Reading Passage — Grade 6 English Language Arts
Name: ____________________________ Date: ______________

Passage

The snow at Winnock Pass is deep enough in March to bury a parked car. Aleta Ferris parks below the last switchback and walks the final half mile on skis, pulling a sled behind her. In the sled she carries a hollow aluminum tube, a spring scale, and a notebook with waterproof pages.

Aleta measures snow for the fictional Ferniehurst Water District. The district serves a town of about 14,000 people in the valley, and nearly all of its summer water comes from the Marrow River. That river begins at the pass where she is standing.

Her work follows a route called a snow course. It is a line of ten marked points, set in the same places every year since her grandmother's time. At each point Aleta pushes the aluminum tube straight down until it reaches the ground. She reads the depth off the marks on the side of the tube. Then she lifts the tube, with the plug of snow still inside it, and hangs it from the spring scale.

The weight is the number that matters. Snow is mostly air, and two snowfalls of the same depth can hold very different amounts of water. Light, dry powder may hold only a little. Heavy, wet snow that has settled and refrozen holds much more. When Aleta weighs the plug of snow, she can calculate how deep the water would be if all of that snow melted at once. That figure is called the snow water equivalent, and it is what the district actually needs.

At the fourth point, the tube goes down 51 inches before it hits the ground. The snow water equivalent works out to 14 inches, which is a little above the average for that point in her notebook. At the seventh point, near a stand of trees that shade the snow from the afternoon sun, the depth is lower and the water equivalent is higher. Aleta writes both numbers down without adjusting either one.

The snowpack works like a reservoir that nobody built. Rain that falls in a valley runs downhill within hours and leaves, while snow that falls on a mountain stays where it lands, sometimes for five months, and then releases its water slowly as the weather warms. That slow release is why the Marrow River keeps running in July, long after the last storm.

Every drop of that water comes off the same slopes. The land that drains into one river is called a watershed, and Ferniehurst sits at the bottom of this one. A change high in the watershed reaches the town eventually, whether that change is a wet March, a dry one, or a warm spring that melts the snowpack faster than the reservoir downstream can hold the runoff.

Aleta finishes the ten points a little after two o'clock. She has been on the snow for five hours. Back at the trailhead she enters the numbers into a form that goes to the district, the state, and the farms on the valley floor. The reading from the pass will help the district decide, in March, whether to plan for an ordinary summer or to ask residents in June to cut back on outdoor watering.

She checks the notebook once before closing it. Her grandmother measured this same course, at these same ten points, with the same kind of tube. The technology has hardly changed, because the question has not changed either. Somebody still has to walk up the mountain, pull out a plug of snow, and weigh it.

Questions

  1. Why does Aleta measure the weight of the snow rather than only its depth?
  2. What is snow water equivalent, according to the passage?
  3. What does the passage mean when it calls the snowpack a reservoir that nobody built?
  4. At the seventh point, the depth was lower but the water equivalent was higher. Using the passage, explain how that is possible.
  5. Explain what a watershed is, and name the watershed Ferniehurst sits at the bottom of.
  6. The passage says the March reading helps the district decide what to do in June. Explain why a measurement taken in March can predict a problem five months later.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key
  1. Answer: Because snow is mostly air, and two snowfalls of the same depth can hold different amounts of water. The passage states that light powder holds little water while heavy, settled snow holds much more, so weight tells the district what depth alone cannot.
  2. Answer: It is how deep the water would be if all of the snow melted at once. Aleta calculates it from the weight of the plug of snow in her tube.
  3. Answer: It means the snowpack stores water the way a reservoir does, without anyone building it. The passage explains that snow stays on the mountain for months and then releases its water slowly as the weather warms.
  4. Answer: The snow at that point must be denser, packed and settled like the heavy, wet snow the passage describes, so it holds more water in less depth. That is why the shallower reading on the tube produced the higher weight. Accept any answer that explains the difference by density; the passage does not say why this point's snow is denser.
  5. Answer: A watershed is the land that drains into one river. Ferniehurst sits at the bottom of the watershed that drains into the Marrow River, which begins at Winnock Pass.
  6. Answer: Answers will vary. A strong response explains that the snowpack is the source of the summer river flow, so measuring how much water is stored in the snow in March tells the district how much will be available later, which is why a light snow year leads to watering limits in June.

Differentiation

Support

Give these students the passage with the four key sentences about weight, snow water equivalent, the natural reservoir, and the watershed already highlighted. Let them answer questions 1, 2, 3, and 5 first, and provide the frame "Depth tells us ___, but weight tells us ___" for question 1.

Extension

Ask students to write the four-sentence report Aleta would send to the district after a March with half the usual snow water equivalent, using the passage's details and stating one action the district should consider. Then have them name the sentence in the passage that most supports their recommendation.

ELL supports

Pre-teach "snowpack," "snow course," "melt," "runoff," and "watershed" with a labeled drawing of a mountain, a river, and a town below. Allow students to answer questions 1 through 3 with short phrases, and let them explain question 4 aloud with a partner before writing.