Scales of Change on Earth's Surface

1. Period 1: Presentation slides 1-8 (Yosemite phenomenon, targets, weathering, erosion, deposition, the sand grain's path, the agents of change). W1 phenomenon worksheet opens the period; W2 vocabulary relationships closes it.
2. Period 2: Lab 1 session 1 (make the saturated solutions and set up the fast- and slow-cooling cups). Then slides 9-10 (space scale ladder, the 'can a change you cannot see build a dune?' discussion). W3 reading passage as homework.
3. Period 3: Lab 1 session 2 at the start (choose and measure the largest crystal; daily 5-minute check-ins begin). Slides 11-16 (slow changes, uplift and rate vocabulary, the rate check, fast changes, the two-rulers chart, the big-and-fast check). W5 data worksheet on rates follows.
4. Period 4: Lab 2, the valley evidence mystery (one session). Slide 17 (the San Andreas connection at Wallace Creek) fits at the end as a real version of the slow-sum, sudden-jolt pattern. W8 collaborative worksheet uses the same evidence-sorting skill if Lab 2 is skipped.
5. Period 5: Lab 3, the campus field investigation of rates (one session outdoors; indoor abrasion alternative if the grounds or weather do not allow). W4 diagram worksheet on the hoodoo model can be homework.
6. Period 6: Lab 1 session 3 (final crystal measurement, graph, rate, extrapolation, fast-versus-slow cooling comparison). Slides 18-23 (rate detectives task, hoodoo patterns and model, the 'fifty years from now' discussion, uniformitarianism, the uniformitarianism check). W7 misconception repair.
7. Period 7: Slides 24-26 (misconception about the unchanging cliff, synthesis, exit ticket). W6 CER on the Yosemite evidence as the written assessment; W9 transfer task for students who finish early; W10 mastery as the quiz.

Materials overview: Lab 1 needs alum (potassium aluminum sulfate, sold in the grocery spice aisle) or Epsom salt, clear sturdy cups, hot water from a kettle that only the teacher handles, goggles, millimeter grid paper and rulers. Lab 2 needs only printed evidence cards, a printed space-time grid and the recording sheet. Lab 3 needs tape measures, millimeter rulers, a straightedge, chalk, a camera or phone for photographs, clipboards and access to the school grounds; the indoor alternative needs lidded jars, sidewalk chalk and aquarium gravel. No open flames anywhere in the chapter.

• Multilingual learners: Pre-teach the four process verbs as actions with gestures (break, carry, drop, lift) and post them with pictures; provide the two-rulers chart with the axis labels in the home language and English; pair students for Lab 2 so each evidence card is read aloud and paraphrased before it is placed.
• Students who need more support: Give a rate-calculation frame (change ÷ time = rate; rate × time = change) with units pre-filled; supply the Lab 1 table with day numbers and the graph axes already scaled; reduce the Lab 2 card set to eight cards with the two clearest sudden events kept in.
• Students ready for extension: Ask them to estimate how many freeze-thaw cycles a Bryce Canyon hoodoo has survived if the site averages about two hundred a year and the pillar is ten thousand years old, to research why the Grand Canyon's age is debated among geologists, or to design a rate measurement for their own neighborhood.
• Students who need movement or alternative output: Run the time scale as a floor line across the room with students holding process cards and physically stepping to their position; let the Lab 2 explanation be recorded as a two-minute spoken 'geologist's report'; allow the hoodoo model (W4) to be built from stacked foam or clay instead of drawn.
• Students with low vision or limited fine-motor control: Provide large-print evidence cards and a tactile scale strip with raised markers; in Lab 1 let a partner read the ruler while the student records and calls out the daily value; in Lab 3 assign the measuring role to a partner and the recording and rate-calculating role to the student.

• Uniformitarianism (pp. 141, 148, 149): the book says processes happened 'in the same way' in the past and act 'the same way everywhere'. Teach the modern version: the same kinds of processes and the same natural laws operate across time, but rates and intensities vary (ice ages, wetter or drier climates), and sudden catastrophic events are part of Earth's history. Never assess 'same rate'.
• Stromatolites (p. 147): the Key Science Concept card calls them the remains of algae colonies. Stromatolites are layered mounds built by mats of cyanobacteria (microbes once called blue-green algae) trapping sediment. Also, the chart's 'billions of years' for this card is how old the oldest fossils are, not how long one took to form; keep stromatolites off any 'how long does this process take' task.
• Continental motion (p. 144): the book gives 1 to 3 cm per year. Plates move at different speeds; the Australian plate moves about 7 cm per year, and seafloor spreading rates run from under 2.5 to over 15 cm per year. Say 'a few centimeters a year, about as fast as fingernails grow' and use a stated rate in any calculation.
• Sandstone (p. 144): the book says the weight of overlying layers cements sand together. Weight compacts the grains; cementation happens when minerals carried by groundwater are deposited between the grains and glue them. Teach both steps by name.
• Caves (p. 144): the book says a chemical reaction between water and limestone dissolves the rock. Add that the water is weakly acidic because it carries dissolved carbon dioxide (carbonic acid), which is why it can dissolve limestone. Cave passages widen by about a millimeter a year at most.
• Eruption length (p. 145): the book says eruptions can last several weeks. Historic eruptions have lasted from under a day to decades or longer; a typical one is on the order of weeks. Treat 'weeks' as typical, not a rule.
• Asteroids (p. 145): the book defines an asteroid as a mountain-sized chunk of rock. Asteroids range from a few meters to about 500 km across. Say 'a rocky body orbiting the Sun; the ones that leave big craters are kilometers across'.
• Flash floods and landslides (p. 145): heavy rain over a short time is the usual cause of a flash flood, but so are a dam or levee failing and an ice or debris jam letting go. Earthquakes trigger landslides, not floods; the book's sentence linking both to 'unstable ground' fits landslides only.
• Namib Desert (pp. 142-143): it lies along the southwest coast of Africa, mostly in Namibia, not 'western Africa'. Its tallest dunes are a little over 300 m (the book says 240 m). The 80,000 km² figure is close to the whole desert, which includes rocky plains; the sand sea itself is about 34,000 km². The 55-million-year figure is an estimate of the desert's age, not a measured age of the sand; individual dunes dated so far are thousands of years old.
• Uplift timing (pp. 141, 144, 146): the lesson gives 100 million years, 'hundreds of millions of years' and 'about 30 million years' (Rockies) in different places. Say that uplift raises mountain ranges over millions to tens of millions of years, and do not assess a specific figure. Also, uplift is not always slow: in the 1964 Alaska earthquake land rose as much as about 11 m within a few minutes.
• Eruption area (p. 147): the card says eruptions can add hundreds of thousands of km² of new material in days or months. Lava fields that large took hundreds of flows over about a million years. Ash fall can blanket tens of thousands of km² in hours (Mount St. Helens in 1980 covered more than 57,000 km² in about nine hours), so the claim fits ash, not lava.
• Crystal timing (p. 147): the card says crystals several meters across form as magma cools over tens of millions of years. Growth times for giant crystals vary enormously and this figure could not be verified. Lab 1 uses the crystal as a model of slow, invisible growth that adds up, not as a measured geologic rate; the Naica cave's gypsum crystals, up to about 11 m long, are estimated to have grown over hundreds of thousands of years.
• Hoodoos (p. 148): the book says hoodoos everywhere formed 'the same way'. The general recipe is shared (a tougher cap protects a softer pillar), but the details differ by site. At Bryce Canyon, frost wedging during about two hundred freeze-thaw cycles a year and weakly acidic rain do most of the work.
• Grand Canyon (p. 146): the card gives about 5 million years for the canyon's formation. The age of the connected canyon is commonly placed at 5 to 6 million years, but some segments may be much older and geologists still debate it. Use the depth (about 1.6 km) with a stated age for any rate calculation, and say the age is an estimate.
• The time-and-space chart (pp. 146-147): each step on the axes is a jump of many times the step before, so distances on the chart do not show true proportions of time or size. Point this out before students read placements from it.
• Weathering by organisms (p. 142): the beetle grinding sand grains is physical weathering by abrasion. Living things also weather rock chemically (lichens, plant acids) and physically (roots). Both count.
• Yosemite phenomenon: the valley was deepened by glaciers during several ice ages over roughly the last two million years; the last glacier to fill the valley melted back about fifteen thousand years ago. The park documents dozens of rockfalls in a typical year; the figure varies from year to year, so avoid quoting one exact number.