### Introduction to Perimeter and Area

1. **Define Perimeter and Area:**
- Define what perimeter and area are for plane shapes.
- Explain the difference between them and their importance in geometry.

2. **Triangles:**
- Discuss different types of triangles (e.g., equilateral, isosceles, scalene).
- Introduce formulas for calculating the perimeter and area of triangles.
- Provide examples and step-by-step calculations for each type of triangle.

3. **Trapeziums:**
- Define what a trapezium is and its properties.
- Present the formula for calculating the perimeter of a trapezium.
- Explain how to find the area of a trapezium using the formula involving the bases and height.
- Include examples illustrating the calculations.

4. **Parallelograms:**
- Discuss the properties of parallelograms.
- Present formulas for calculating the perimeter and area of parallelograms.
- Provide examples with detailed calculations.​