Measurement Length and Perimeter - Perimeter of Rectilinear Shapes - Presentation

In Lesson 9, students are introduced to the concept of calculating the perimeter of rectilinear shapes. The lesson begins with a discussion prompt, encouraging students to identify two properties of rectilinear shapes. The main focus of the lesson is to find the perimeter of various rectilinear shapes through a series of activities. Students are presented with diagrams of shapes with given measurements, and they are tasked with determining the missing measures to calculate the total perimeter. For instance, they are shown a shape with sides measuring 4 cm, 6 cm, 8 cm, and other lengths, and they must add these together to find the perimeter, which in one example totals 44 cm.

Further activities involve more complex shapes, including ones made from identical rectangles, prompting students to explore different methods such as using bar models to assist in their calculations. A creative challenge is posed to students to construct different shapes with a perimeter of 24 cm and to consider the number of sides these shapes have. Additionally, reasoning tasks involve determining possible perimeters of a rectilinear shape where all sides are of equal length and are whole numbers of centimetres. Students are encouraged to think critically about their answers, understanding that the correct perimeters are multiples of the number of sides. The lesson includes independent work where students use given measurements to calculate perimeters and engage in discussions to deepen their understanding of rectilinear shapes and the concept of perimeter.