Angela's Tools · Chapter 18 · The Water Cycle
Worksheet 8 of 10
Twelve Places, One Cycle: An Evidence Jigsaw on Sun, Cooling and Gravity
Learning target: I can use evidence from many places on Earth to sort water cycle processes by their driver, trace several different routes a water molecule could take, and defend the idea that the cycle has no fixed order.
Collaborative investigationAbout 55 minJigsaw
MS-ESS2-4 · practice
collaborationdiscussiondata analysis
NameDatePeriod
Directions
Work in home groups of four. Step 1 (expert round, 12 minutes): each member takes one 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 students from other groups who hold the same set. Together, agree on what process each card shows, what drives it, and the one line of evidence that proves it. Step 2 (home round, 25 minutes): return to your home group, teach your three cards in under two minutes each, and complete the group task. Step 3 (defense, 8 minutes): present one of your routes to a neighboring group, who will try to find a step that could happen in a different order. Step 4 (individual, 10 minutes): answer Part C alone.
You will need: One set of twelve cards per group (cut from this sheet or printed separately), This worksheet, one per student, Pencil, Desk space for three columns
Twelve evidence cards: observations from twelve places
1 Card 1: Ocean surface, sunny afternoonA buoy reports surface water at 24 °C and the air just above it getting steadily more humid through the afternoon. The water never comes close to boiling. On a dry, windy day the surface temperature drops slightly even in full sun, as if something were carrying energy away.
2 Card 2: Oak branch with a bag over itA clear plastic bag tied over a leafy branch collects 30 mL of water in one sunny day and 5 mL on a cloudy day. Under a microscope the underside of each leaf shows thousands of tiny pores. A branch with its leaves removed collects almost nothing.
3 Card 3: Glacier edge, JulyMeltwater streams at the foot of the ice run hardest at about 4 p.m. and slow to a trickle before dawn. On an overcast day the afternoon peak is much smaller. The ice surface is dirty gray in late summer and melts faster than the clean white snow beside it.
4 Card 4: Air rising over a ridgeA weather balloon shows that air pushed up the side of a mountain cools by roughly 1 °C for every 100 m it climbs. The flat bottom of the clouds sits at exactly the height where the air has cooled enough that it can no longer hold all of its vapor. Above that height, the balloon's sensor is wet.
5 Card 5: Kitchen window, winter morningIndoors the air is 21 °C and moist from cooking; outside it is −2 °C. The inside of the window is covered in liquid drops by morning, while the outside of the window is dry. The drops are pure water even though the air carried smells of soup.
6 Card 6: Car windshield, clear cold nightThe windshield is dry and clean at sunset. After a clear night at −5 °C it is covered with feathery ice crystals at dawn. No drops of liquid were ever seen on it, and no rain or snow fell.
7 Card 7: Inside a rain cloudCloud droplets are about a hundredth of a millimeter across and float on rising air. They bump into one another and merge. When they reach about a millimeter across they begin to fall. High-speed photos show large falling drops flattened on the bottom like a bun, and the very largest break apart in the air.
8 Card 8: Two slopes in the same stormA rain gauge records 20 mm of rain. On a grassy hillside, water begins trickling into the ditch at the bottom after about an hour. On a paved parking lot beside it, water is streaming into the storm drain within two minutes, and the stream is much larger.
9 Card 9: Two soil columnsA cup of water poured onto a tube of sandy soil disappears into it in seconds and drips out the bottom a minute later. The same cup poured onto a tube of tight clay sits on top as a pool for most of an hour. Both tubes are held upright; when the sandy tube is laid flat, the dripping stops.
10 Card 10: Valley well and a springThe water level in a farm well rises about two weeks after heavy rain on the hills above, not during the rain. Harmless dye poured into a sinkhole on the hill appears at a spring 3 km downhill 40 days later. The spring keeps flowing through a rainless summer.
11 Card 11: Fog net on a desert hillsideOn foggy mornings a mesh net stretched between poles becomes wet, drops run down the mesh into a gutter and the gutter drains into a tank. The droplets in the fog are far too small to fall as rain on their own. Output is highest on windy fog days and zero on clear days.
12 Card 12: Earth's water inventoryScientists estimate that about 96.5 percent of Earth's water is in the oceans, 1.74 percent is frozen in glaciers and ice caps, 1.69 percent is groundwater, 0.013 percent is in lakes, and only about 0.001 percent is in the atmosphere at any moment. Yet it rains or snows somewhere on Earth every day, and a typical water molecule stays in the air for only about a week to ten days before falling out.
Part A: Expert round (one set per person)
1.For each of your three cards, write: the process it shows (or the storage place), the driver (sun's energy, cooling, or gravity), and the single sentence of evidence on the card that proves the driver. Agree on these with the other experts who hold your set.
Part B: Home group task
- Each expert teaches their three cards. Listeners write the process and driver for every card in the group table below.
- Lay the twelve cards on the desk in three columns: sun's energy (water gains energy), cooling (water gives off energy), gravity (water moves down or downhill). Two cards are about storage or a built device rather than one process; decide together where they belong and write a note explaining your choice.
- Check every column with the test question: for the sun column, does the card's evidence change with sunlight? For the cooling column, does the card show water appearing where it is cold? For the gravity column, does the card show water moving down, and does it stop when there is no 'down' (Card 9)?
- Trace three routes a single water molecule could take through at least five different cards each, writing the card numbers in order (for example 1, 4, 7, 8, 10). No two routes may share more than two cards, and at least one route must never visit the ocean.
- Prepare a one-minute defense of this claim: 'The water cycle has no fixed order.' Use at least two of your routes and Card 12 as evidence. Every member must be able to give the defense.
Group record (fill in)
| Card | Process or storage | Change of state (if any) | Driver | Evidence sentence (short) |
|---|
| 1 | | | | |
| 2 | | | | |
| 3 | | | | |
| 4 | | | | |
| 5 | | | | |
| 6 | | | | |
| 7 | | | | |
| 8 | | | | |
| 9 | | | | |
| 10 | | | | |
| 11 | | | | |
| 12 | | | | |
2.Write your three routes as lists of card numbers, each with a one-line description of the molecule's trip. Mark the route that never visits the ocean.
3.Record the challenge the neighboring group made to your route and how your group answered it. If they found a step that really could happen in a different order, say so and explain why that supports the 'no fixed order' claim rather than hurting it.
Part C: Individual accountability (complete alone)
4.Which card proves that evaporation happens far below boiling? Quote the evidence and explain what the slight cooling of the surface on a windy day tells you about where the energy went.
5.Cards 4, 5 and 6 all belong in the same column. What do they have in common, and what is the one difference between Card 6 and the other two?
6.Using evidence from at least three cards (one from each driver column), explain why the water cycle needs both the sun's energy and gravity, and what would happen to the cycle if either one stopped.
7.Card 11 describes a fog net. Name every water cycle process that happens from the time ocean water becomes fog to the time water reaches the tank, and say which driver is responsible for each step.
If the sorting stalls
Use the fastest clue on each card. Does the card mention sunlight, afternoon, or a sunny versus cloudy difference? It belongs under the sun's energy. Does water appear on something cold, or where air has cooled? It belongs under cooling. Does the card describe water moving downhill, dripping, draining or falling? It belongs under gravity. Cards 11 and 12 are special: Card 11 contains several processes, and Card 12 is about how much water is stored where. Put those two aside and sort them last, as a group.
The thirteenth card
Write a thirteenth evidence card for a place the deck does not cover (ideas: a snowfield on a cold, dry, sunny day; a desert playa after a flash flood; a greenhouse; the inside of a cave). The card must contain at least one observation that identifies the driver and at least one number. Then write its key: the process, the change of state if any, the driver, and the route it could join. Trade cards with another group and sort each other's.