Calculating Circumference Using the Radius

MatholiaChannel

This educational video provides a clear, step-by-step demonstration of how to calculate the circumference of a circle when the radius is known. Through two distinct examples, the video illustrates the application of the formula C = 2 × π × r. The first example uses a real-world object (a clock) and treats Pi as the fraction 22/7, highlighting how to simplify equations with fractions. The second example uses an abstract circle and treats Pi as the decimal 3.14, demonstrating calculation strategies with decimals. The content focuses on core geometry concepts including identifying the radius, recalling the correct formula for circumference, and substituting values into that formula. It specifically addresses mathematical fluency by showing different ways to handle the constant Pi depending on the context or instructions given. The visual layout separates the problem statement from the working out, reinforcing organized mathematical thinking. For the classroom, this video serves as an excellent model for procedural fluency in geometry. It is particularly useful for teaching students how to set up their work, substitute variables, and perform calculations accurately. The contrasting examples help students understand that Pi can be represented in multiple ways and that the choice of representation can sometimes simplify the calculation process, specifically when the radius is a multiple of 7.