A rock cycle lesson that starts with a rock each student found

Why this matters

A student can name igneous, sedimentary and metamorphic and still call a striped rock sedimentary, because stripes look like layers. Her claim is wrong, and her reasoning is a rule of thumb: "metamorphic rocks have stripes". On a worksheet the reasoning line gets one word of feedback, and the teacher has to wait for quiz day to find out who can explain how their rock formed.

Maya's rock from a hike

Maya is a middle schooler who picks up rocks on hikes with her family. She knows the three rock types by name. She thinks any rock with stripes is sedimentary.

Every student in the class gets the same greeting, the same three sample rock photos and the same path: identify the rock, trace it through the rock cycle, then write a claim, evidence and reasoning. Each student photographs their own rock or picks a sample, so each chat starts from a different rock, and Sparky's next message depends on what that student just wrote.

Sparky uses Maya's photo and what she noticedSparky sends Maya back to something she already saidA right answer gets a harder question

M

Maya

Interest: Hiking with her familyStarting point: Thinks stripes mean sedimentary

Sparky

Hi! Today you're a rock detective. Send me a photo of a rock you found: in your yard, at a park, by a creek, anywhere. No rock? Pick Rock A, B or C from the photos. Before you send it, look closely. What's one thing you notice about your rock?

Maya

i found this on a hike with my family. it has stripes and little shiny red dots in it

Sparky

That's a great find from your hike! I can see those stripes and the little reddish spots you're talking about. Do the stripes look like flat, even layers, like pages in a book, or more wavy, like they got squeezed or bent?

Maya

pretty flat i think. so its sedimentary, it has layers like the cliffs at the beach

Sparky

Good thinking connecting layers to what you've seen before! But look closely at one more thing before you decide. Those shiny red dots: do they look like sand grains or pebbles glued together, or more like crystals that grew inside the rock?

Maya

they look like tiny crystals, not sand. so is it metamorphic? like the crystals got squeezed into stripes

Sparky

Yes, you've got it! The crystals squeezed into stripes is exactly the right reasoning. Your metamorphic rock is highlighted on the diagram. Click any process arrow to see what your rock becomes next. What process do you think created your rock in the first place?

Maya

heat and pressure! it was a different rock deep underground and it got squeezed so the crystals lined up in stripes

Understanding check

Exactly right. That's the process that made your rock. Now a harder question: what would have to happen to turn your metamorphic rock into a sedimentary rock?

Maya

it would have to get broken into tiny pieces by weathering and erosion

Sparky

Good start, that's the first step! But you're not at sedimentary rock yet. What happens to those tiny pieces after they get broken off and carried away? Follow the arrows one more step in the interactive.

Maya

oh they become sediment, then they get pressed down and glued together. compaction and cementation. then its sandstone

Sparky

Perfect, you traced the whole path! Now write your CER. Claim: what type of rock is it? Evidence: at least two things you can see in your rock. Reasoning: how did it form, and why does your evidence point to that type?

Maya

claim: my rock is metamorphic. evidence: it has stripes and tiny red crystals. reasoning: metamorphic rocks have stripes

Sparky

Great claim and evidence! Your reasoning needs a bit more though. Why do metamorphic rocks have stripes? And what do the red crystals tell you about how it formed?

Maya

reasoning: it was a different rock deep underground. heat and pressure squeezed it without melting it, so the crystals lined up in stripes. the red crystals grew in the rock, they arent sand grains glued together, so it cant be sedimentary

Sparky

That's a strong CER. Your claim is clear, your evidence is two things you can see, and your reasoning explains how the rock formed and uses the crystals to rule out sedimentary.

Called her rock sedimentary, fixed it from her own clue, then wrote a full CER

Maya and her chat are an example. We ran the library activity in Flint as a test student, sent a photo of a striped rock with red crystals, and typed Maya's messages. Sparky's replies are its own words from that run, shortened, with emoji removed.

What Flint did for Maya

• Flint read Maya's photo, and Sparky's first reply asked about the stripes and red spots in it.
• When Maya called her rock sedimentary because of the stripes, Sparky asked about the red crystals she had pointed out and didn't give the answer.
• Once Maya named the right type, Sparky built a rock cycle she could click, with her rock marked on it.
• When her answer to the harder question stopped at weathering and erosion, Sparky sent her to the next arrow in that rock cycle.
• Sparky asked for her answer as a claim, evidence and reasoning, and asked her to redo only the reasoning when it was a rule of thumb.

A teacher can't do this by hand for 30 students, and Sparky does it in every student's chat.

The activity page shows who is still guessing from stripes

While the class works, Needs attention shows the teacher which student is stuck and on which message. After three or more students submit, activity analytics lists what the class explained well, where students went wrong, and a follow-up to practice next.

Set up the activity for free

The rock activity is in Flint's public library, with the three sample rock photos, Sparky's guidelines and the greeting already written. Open it, select Try this activity to copy it into a free Flint account, and assign it to a class. Students who can't photograph a rock pick Rock A, B or C, so the activity runs in class the same day.

For more science activities, see Flint for science.