4.MD.6 Measuring angles with a protractor worksheet - Free Printable

Let's solve this step by step. The task is to measure each angle shown on the protractor and write down the measurement.

We’ll go through each of the five diagrams one by one.

---

🔹 Diagram 1 (Top Left)

- The base line of the angle is aligned with the 0° mark on the right side (the outer scale).
- The other ray points to 130° on the outer scale.
- Since we start from 0° on the right, we read the outer scale.
- ✔ Angle = 130°

---

🔹 Diagram 2 (Top Right)

- The base line is aligned with the 0° mark on the right (outer scale).
- The other ray points to 70° on the outer scale.
- ✔ Angle = 70°

---

🔹 Diagram 3 (Middle Left)

- The base line is aligned with the 0° mark on the left (inner scale).
- The other ray points to 80° on the inner scale.
- ✔ Angle = 80°

---

🔹 Diagram 4 (Middle Right)

- The base line is aligned with the 0° mark on the left (inner scale).
- The other ray points to 50° on the inner scale.
- ✔ Angle = 50°

---

🔹 Diagram 5 (Bottom Center – Two Rays)

This one shows two rays forming two angles. We need to measure both angles, but likely the goal is to find the angle between the two rays.

Let’s analyze:

- The left ray points to 40° on the outer scale.
- The right ray points to 140° on the outer scale.
- But wait: since both rays are measured from the center, we can compute the angle between them.

But actually, in this case:
- The left ray is at 40° (on the outer scale, from the right).
- The right ray is at 140° (also on the outer scale).

Wait — that would mean the angle between them is:

> 140° - 40° = 100°

Alternatively, if we look carefully:
- The left ray is pointing at 40° on the outer scale (from the right), so it's 40° from the right.
- The right ray is pointing at 140° on the outer scale (from the right), so it's 140° from the right.
- But that would imply the angle between them is 100°, because 140 - 40 = 100.

But let’s double-check using the inner scale:

- From the center, the left ray goes to 140° on the inner scale? No — better to use consistent reference.

Actually, here’s a better way:

The protractor has two scales:
- Outer scale: 0° on the right → increases counterclockwise
- Inner scale: 0° on the left → increases clockwise

In Diagram 5:
- The left ray crosses the 40° mark on the outer scale (which corresponds to 140° on the inner scale? Let's not confuse).

Better method: Use the same scale for both rays.

Let’s use the outer scale:
- Base line is horizontal, centered.
- Left ray: points to 40° on the outer scale (from the right)
- Right ray: points to 140° on the outer scale (from the right)

So the angle between them is:

> 140° - 40° = 100°

✔ So the angle between the two rays is 100°

Alternatively, you could say the angle formed at the vertex is 100°.

---

✔ Final Answers:

| Diagram | Angle Measurement |
|--------|-------------------|
| 1 (Top Left) | 130° |
| 2 (Top Right) | 70° |
| 3 (Middle Left) | 80° |
| 4 (Middle Right) | 50° |
| 5 (Bottom) | 100° |

---

📝 Summary:

You would write these answers in the boxes provided (if there were boxes), like:

- Box 1: 130°
- Box 2: 70°
- Box 3: 80°
- Box 4: 50°
- Box 5: 100°

---

💡 Tip: Always check which scale (inner or outer) you're reading from based on where the 0° is aligned. If the base line starts at 0° on the right, use the outer scale. If it starts at 0° on the left, use the inner scale.

Let me know if you want a visual explanation or how to draw these angles!