Bio interactive activity for 10 - Free Printable

Let’s go step by step to fill in the blanks using the vocabulary words provided.

We have these terms to use:
- Cambrian explosion
- era
- fossil
- geologic time scale
- half-life
- K-T boundary
- law of superposition
- paleontologist
- period
- plate tectonics
- radiometric dating
- relative dating

Now, let’s read the paragraph and match each blank with the correct term.

---

First sentence:
> Scientists measure Earth’s geological and biological events using the ________________, which is divided into ____________ and ____________.

The big system scientists use to organize Earth’s history is called the geologic time scale. It’s broken down into large chunks called eras, and those are further divided into smaller chunks called periods.

So:
→ First blank: geologic time scale
→ Second blank: eras
→ Third blank: periods

*(Note: The word “era” and “period” are both in the list — we’ll use them here.)*

---

Next sentence:
> The ________________ is the name of a period of rapid change during which the ancestors of most animal groups emerged.

This is referring to a famous event in Earth’s history when many new animal forms appeared suddenly (in geologic terms). That’s the Cambrian explosion.

→ Blank: Cambrian explosion

---

Next:
> A layer of soot found between rock layers worldwide, known as the ________________, might indicate that a large meteorite collided with Earth.

This refers to a specific layer linked to the extinction of dinosaurs — the K-T boundary (Cretaceous-Paleogene boundary).

→ Blank: K-T boundary

---

Next paragraph:
> The theory of ________________ describes Earth’s surface as large plates that move over Earth’s thick, liquid interior.

That’s plate tectonics — the theory about moving continental plates.

→ Blank: plate tectonics

---

> These plates are made up of various types of rocks. ________________ are scientists who study ________________.

Scientists who study fossils are called paleontologists. And they study fossils.

→ First blank: Paleontologists
→ Second blank: fossils

*(Note: “paleontologist” is singular in the list, but since the sentence says “are scientists”, we pluralize it naturally.)*

---

> They determine the relative age of rocks using ________________, which compares the sequence of rock layers.

Comparing rock layers to see which is older or younger is called relative dating.

→ Blank: relative dating

---

> The ________________ states that younger rock layers are deposited on top of older rock layers.

That’s the law of superposition — a basic rule in geology.

→ Blank: law of superposition

---

> Another method of determining the age of rocks is ________________, which measures the decay of radioactive isotopes.

Measuring radioactive decay to find absolute ages is radiometric dating.

→ Blank: radiometric dating

---

> The rate of decay can be measured using ________________, the amount of time required for half of a radioactive isotope to decay.

That’s the definition of half-life.

→ Blank: half-life

---

✔ Now let’s put all the answers in order as they appear in the paragraph:

1. geologic time scale
2. eras
3. periods
4. Cambrian explosion
5. K-T boundary
6. plate tectonics
7. Paleontologists
8. fossils
9. relative dating
10. law of superposition
11. radiometric dating
12. half-life

---

Final Answer:
geologic time scale, eras, periods, Cambrian explosion, K-T boundary, plate tectonics, Paleontologists, fossils, relative dating, law of superposition, radiometric dating, half-life