Angela's Tools · Chapter 11 · Scales of Change on Earth's Surface Worksheet 8 of 10

Scale Sorters: Twelve Earth Events on Two Rulers

Learning target: I can work with a team to place Earth events on a time-and-space chart, find the patterns the chart reveals, and defend our placements with the numbers on the cards.

Collaborative investigationAbout 50 minJigsaw MS-ESS2-2 · practice collaborationdiscussiondata analysis
NameDatePeriod

Directions

Work in home groups of four. Step 1 (expert round, 10 minutes): each member takes one expert set of three cards (Set A: cards 1-3; Set B: cards 4-6; Set C: cards 7-9; Set D: cards 10-12), reads them, and meets with the other students who hold the same set to agree on each card's space category and time row. Step 2 (home round, 20 minutes): return to your home group, teach your cards, and complete the group task: build the chart, fill the group record, and find the patterns. Step 3 (defense, 10 minutes): present your chart to a neighboring group, who will challenge at least two placements. Step 4 (individual, 10 minutes): answer Part C alone.

You will need: Twelve cards per home group, cut from the card sheet, One sheet of poster paper per group, Markers, Group record table, Calculator for Part C

Twelve event cards (sizes and times are teaching values, rounded to be realistic)
1 Card 1: Beetle on a duneA beetle crosses a sand dune. Each step presses grains against each other and chips a few. Space: a few millimeters. Time: seconds. Agent: a living thing. The same tiny grinding happens every time anything walks on sand.
2 Card 2: Glacier carves a valleyA glacier flows down a mountain valley, dragging rock frozen into its base. It deepens the floor about 1 mm per year and over 100,000 years turns a V-shaped valley 20 km long into a U shape. Space: 20 km. Time: 100,000 years. Agents: ice carrying rock, and gravity.
3 Card 3: Lava buries a valleyA volcano erupts. Over three weeks, lava flows bury a valley 10 km long under new rock. Space: 10 km. Time: weeks. Setup: magma had been collecting beneath the volcano for centuries before the eruption.
4 Card 4: Hoodoo cap fallsA hoodoo's soft pillar has thinned for tens of thousands of years under its hard cap. One morning the 2 m cap tips and falls in about 3 seconds. Space: about 10 m. Time of the fall: seconds. Time of the setup: tens of thousands of years.
5 Card 5: Cave passage growsWeakly acidic groundwater dissolves limestone along a crack, widening it by about 1 mm per year at most. A passage 2 m wide took at least 2,000 years; the whole cave system is about 500,000 years old. Space: a few km of passages. Time: hundreds of thousands of years. Agent: water (chemical weathering).
6 Card 6: Continent driftsA continent rides its plate at about 2.5 cm per year. Over 100 million years that is 2,500 km. Space: thousands of km (global). Time: 100 million years. Driven by forces inside Earth.
7 Card 7: Flash floodHeavy rain falls upstream. A wall of water scours 15 km of canyon floor in 6 hours, rolling boulders the size of cars. Space: 15 km. Time: hours. Agent: water. Setup: the canyon itself took far longer to form, and loose rock had collected on its floor for years.
8 Card 8: Mountain range risesForces beneath the crust raise a mountain range 500 km long at about 1 mm per year for 30 million years. Space: 500 km. Time: tens of millions of years. Erosion removes rock as the range rises, so the peaks never reach the full height the arithmetic gives.
9 Card 9: Frost splits a boulderWater seeps into a crack in a 1 m boulder, freezes on winter nights and expands, prying the crack wider each year. After about 20 winters the boulder splits in two. Space: 1 m. Time: decades. Agent: ice.
10 Card 10: Dune migratesWind erodes sand from the back of a 100 m tall dune and deposits it on the front, so the whole dune creeps downwind about 1 m per year. Space: hundreds of m. Time to move 1 km: about 1,000 years. Agent: wind.
11 Card 11: Impact dust cools the planetA large asteroid strikes Earth. Within days its dust spreads around the planet and blocks sunlight, cooling the whole surface for months to years. Space: global. Time: days to years. Setup: the asteroid had circled the Sun on the same path for billions of years until that path finally crossed Earth's.
12 Card 12: LandslideAfter a week of heavy rain, a hillside 400 m across gives way and slides into the valley in about 90 seconds. Space: hundreds of m. Time: seconds to minutes. Setup: water soaked the slope for days, and a stream had steepened the slope's base over centuries.

Part A: Expert round (one set per person)

1.Your expert set: ______. For each of your three cards, write its space category (human: mm to m; local: 10s to 100s of m; regional: km to 100s of km; continental or global) and its time row (seconds to hours; days to decades; thousands to hundreds of thousands of years; millions of years or more), and one number from the card that justifies each choice.

Part B: Home group task

  1. On the poster paper, draw a chart with four columns (human, local, regional, continental or global) across the top and four rows (seconds to hours; days to decades; thousands to hundreds of thousands of years; millions of years or more) down the side. Label both rulers.
  2. Each expert places their three cards in the cells they agreed on in the expert round and explains the numbers that justify each placement. The group may move a card only if it can point to a number on the card that was misread.
  3. Fill in the group record table. In the last column, write whether a slow process had to happen first to make the event possible, and name it.
  4. Look for patterns. Find two cards that prove that size and speed are independent. Find every sudden event and its slow setup. Find the cells with the most cards and the cells that are empty.
  5. Prepare a two-minute defense: why each card is where it is, and the two patterns you found. Every member must be able to defend any card, not just their own.
Group record (fill in)
CardSpace categoryTime rowSudden or gradual?Slow setup first? (name it)
1 Beetle
2 Glacier valley
3 Lava flow
4 Hoodoo cap
5 Cave passage
6 Continent
7 Flash flood
8 Mountain range
9 Frost and boulder
10 Dune
11 Impact dust
12 Landslide
2.Group answer: Which two cards did your group choose to prove that size and speed are independent, and what numbers on the cards make the case?
3.Group answer: List every card your group marked 'sudden,' and beside each one write the slow setup that came first. What do these events have in common?
4.Group answer: Write the strongest challenge the neighboring group made to one of your placements, and how you answered it using a number from the card.

Part C: Individual accountability (complete alone)

5.Card 8 says the range rises 1 mm per year for 30 million years. Calculate the total rise in kilometers, showing each unit step. Then explain in one sentence why no mountain on Earth is that tall.
6.Card 10's dune creeps 1 m per year. How many years would it take to cross a 5 km wide valley? Then calculate how far Card 6's continent moves in that same number of years, in meters.
7.A friend says, 'Sudden events just happen; there is no way to see them coming.' Using two cards from the chart, explain why 'sudden' describes how fast an event happens, not whether it had a cause that built up over time.
8.Which card gives the best example of using a process we can measure today to understand the past (uniformitarianism)? Explain what is measured today and what it lets us estimate about the past.

Two questions per card

If your group is stuck on a card, ask only two questions in order. Size: would the change fit in your hand (human), on a sports field (local), across a city or county (regional), or across a continent (continental or global)? Time: did it happen while someone watched (seconds to hours), within a lifetime (days to decades), over many lifetimes (thousands to hundreds of thousands of years), or over a time no person could witness (millions of years or more)? Use the number on the card, not your feeling about how big or slow the event sounds.

Thirteenth and fourteenth cards

Write two new cards of your own, one for an empty cell on your group's chart and one for the most crowded cell. Each card needs a size with a unit, a time with a unit, an agent and, if the event is sudden, its slow setup. Trade cards with another group and place theirs on your chart without looking at their answer. Then write a paragraph on which cells of the chart are hardest to fill with real events and why.

Angela's Tools · Chapter 11 · Scales of Change on Earth's SurfaceWorksheet 8 of 10