Grade 4 · lesson 3 of 4

Order undisturbed sediment layers

Order undisturbed sediment layers using supplied evidence and a solved model.

About 18 minutes, plus any extended practice

Supplied materials

All measurements and observations below are supplied classroom examples. They are not data from actual learners or a claim about a particular real site.
Paper, drawing space or a browser document.
Reference card A: bottom layer of this undisturbed sequence. Reference card B: layer between bottom and top.
Assessment case 1: Which scientific label fits the specifically described step or feature? Supplied case: Three layers: label bottom.
Assessment case 2: Which scientific label fits the specifically described step or feature? Supplied case: Three layers: label central.
Assessment case 3: Which scientific label fits the specifically described step or feature? Supplied case: Three layers: label uppermost.
Assessment case 4: Which scientific label fits the specifically described step or feature? Supplied case: Fault disrupts unknown layers.
Assessment case 5: Which scientific label fits the specifically described step or feature? Supplied case: Lowest of four undisturbed layers.
Assessment case 6: Which scientific label fits the specifically described step or feature? Supplied case: Highest deposited layer in simple stack.

Learn the idea

In a simple undisturbed sequence, lower deposited layers are older than layers above. Folding, faults and intrusions can complicate this rule. Our supplied layers explicitly remain undisturbed.

Oldest means bottom layer of this undisturbed sequence. Middle means layer between bottom and top. Youngest means top deposited layer. Uncertain means disturbance prevents the simple order.

For oldest, look for the clue “bottom layer of this undisturbed sequence.” For middle, look for “layer between bottom and top.” More than one process can happen in a real situation. Answer about the one described in this question.

Read or listen to the four science words and what each means. Say how the first two differ.
Choose two of the short cases. Point to the clue that helps you choose a science word for each one. You may draw or say your answer.
Answer each practice question. Say which clue helped you, then check the explanation.
Use the extra task to make two examples that show different science words. Draw or say what makes each one fit.

Worked example

See the method in action

Worked reference-card problem: a card states “bottom layer of this undisturbed sequence”; a second states “layer between bottom and top.” The first fits oldest and the second fits middle. The reason is the described function or change, not the order of the cards or a favorite name. If their descriptions exchange places, their category labels exchange too. Keep the supplied descriptions attached to the correct case.

Your turn

Check your reasoning

Your answer is temporary and is not saved to an account. Download your current answer before leaving or reloading. Written work on paper or in another app stays in your own file.

Helpful tips

Use the feature “bottom layer of this undisturbed sequence” to justify oldest; do not sort by the name alone.
Distinguish middle (layer between bottom and top) from a different process occurring in the same situation.

See the answer and explanation

oldest

The answer is oldest. In the notes, it means “bottom layer of this undisturbed sequence.” In a simple undisturbed sequence, lower deposited layers are older than layers above. Folding, faults and intrusions can complicate this rule. Our supplied layers explicitly remain undisturbed.

Take it further

Create one new case showing oldest and one showing middle. Expected: the first explicitly shows “bottom layer of this undisturbed sequence”; the second explicitly shows “layer between bottom and top.” Explain the distinction by drawing, speaking or writing. A label without a matching feature is incomplete.

Nothing here is saved to an account or sent to a teacher. The answer download includes your current choice and any checked feedback. It does not include choices from the separate More practice section. Download that section separately.

More practice: try new cases

Choose an answer for each problem. Explain your method on paper, then use the feedback to decide what to revisit.

1. Which scientific label fits the specifically described step or feature? Supplied case: Three layers: label central.uncertainoldestmiddleyoungest

Need a hint?

Look for the described feature: layer between bottom and top.
Compare the clue with each science word. Use only what the case tells you; do not add a new event.

2. Which scientific label fits the specifically described step or feature? Supplied case: Three layers: label uppermost.middleyoungestuncertainoldest

Need a hint?

Look for the described feature: top deposited layer.
Compare the clue with each science word. Use only what the case tells you; do not add a new event.

3. Which scientific label fits the specifically described step or feature? Supplied case: Fault disrupts unknown layers.oldestmiddleyoungestuncertain

Need a hint?

Look for the described feature: disturbance prevents the simple order.
Compare the clue with each science word. Use only what the case tells you; do not add a new event.

Your choices are temporary. Feedback appears after you check all the answers.

Nothing here is saved to an account or sent to a teacher. Keep your own notes or download them before leaving. The score describes these questions; it does not certify subject mastery.

Check the subject sources

These LifeStarter passages, scenarios and exercises are authored for this Academy with AI assistance and review. External resources keep their publishers’ terms. A grade label suggests a starting level; it does not establish alignment with your school’s complete requirements.