Perimeter practice worksheet for Grade 3 students featuring five shapes with side lengths to calculate perimeter.

To solve the problem of finding the perimeter for each shape, we need to calculate the total length of the boundary of each figure. The perimeter is the sum of the lengths of all the sides of a shape.

Let's go through each problem step by step:

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Problem 1:

The shape is a square with side length \(4 \, \text{cm}\).

- Formula for the perimeter of a square:
\[
\text{Perimeter} = 4 \times \text{side length}
\]
- Substituting the given side length:
\[
\text{Perimeter} = 4 \times 4 = 16 \, \text{cm}
\]

Answer for Problem 1:
\[
\boxed{16 \, \text{cm}}
\]

---

Problem 2:

The shape is a rectangle composed of smaller squares, each with a side length of \(3 \, \text{cm}\).

- The dimensions of the rectangle are:
- Length: \(3 \, \text{cm} + 3 \, \text{cm} + 3 \, \text{cm} = 9 \, \text{cm}\)
- Width: \(3 \, \text{cm}\)

- Formula for the perimeter of a rectangle:
\[
\text{Perimeter} = 2 \times (\text{length} + \text{width})
\]
- Substituting the values:
\[
\text{Perimeter} = 2 \times (9 + 3) = 2 \times 12 = 24 \, \text{cm}
\]

Answer for Problem 2:
\[
\boxed{24 \, \text{cm}}
\]

---

Problem 3:

The shape is an irregular polygon. We need to count the total length of the boundary.

- By counting the sides:
- Top: \(5 \, \text{cm}\)
- Right side: \(5 \, \text{cm}\)
- Bottom: \(5 \, \text{cm}\)
- Left side: \(5 \, \text{cm}\)

- Total perimeter:
\[
\text{Perimeter} = 5 + 5 + 5 + 5 = 20 \, \text{cm}
\]

Answer for Problem 3:
\[
\boxed{20 \, \text{cm}}
\]

---

Problem 4:

The shape is a square with side length \(2 \, \text{cm}\).

- Formula for the perimeter of a square:
\[
\text{Perimeter} = 4 \times \text{side length}
\]
- Substituting the given side length:
\[
\text{Perimeter} = 4 \times 2 = 8 \, \text{cm}
\]

Answer for Problem 4:
\[
\boxed{8 \, \text{cm}}
\]

---

Problem 5:

The shape is an irregular polygon. We need to count the total length of the boundary.

- By counting the sides:
- Top: \(4 \, \text{cm}\)
- Right side: \(4 \, \text{cm}\)
- Bottom: \(4 \, \text{cm}\)
- Left side: \(4 \, \text{cm}\)
- Additional vertical segment: \(4 \, \text{cm}\)

- Total perimeter:
\[
\text{Perimeter} = 4 + 4 + 4 + 4 + 4 = 20 \, \text{cm}
\]

Answer for Problem 5:
\[
\boxed{20 \, \text{cm}}
\]

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Final Answers:

1. \(\boxed{16 \, \text{cm}}\)
2. \(\boxed{24 \, \text{cm}}\)
3. \(\boxed{20 \, \text{cm}}\)
4. \(\boxed{8 \, \text{cm}}\)
5. \(\boxed{20 \, \text{cm}}\)