# 11.1: Exploring Cylinders

This is the first section of Chapter 11, "Geometry and Measurement Relationships". The learning goal for this section is to "Explore the relationships between the dimensions of a cylinder and the dimensions of its net". We start this section with an introductory example, where students must find the circumference of a lid and compare it with the dimensions of different labels, to see what matches.
Since this is the beginning of the chapter, we define the concept of *area*, namely "The number of square units needed to cover a region". We then look at a couple of formulas for calculating area, with the understanding that we will soon be calculating the *surface area *of 3D objects.

Finally, we look at nine 2D figures for which we can calculate the area. In the notes, I didn't add the formulas for circumference or area of circles. If you want to learn more about that, Khan Academy has a fantastic explanation.

- Circumference and Area of Circles. This explains how to calculate, well, the circumference and area of circles.
- Circles: Radius, Diameter, Circumference and Pi. This 10-minute video gives a full introduction to the parts of a circle and their basic mathematical properties.
- Labelling Parts of a Circle: Goes over the concepts of radius, diameter, centre and circumference.
- Radius, Diameter and Circumference. A couple short word problems to help check your understanding.
- Area of a Circle Explanation. Explains how to calculate the area of a circle.
- Area of a Circle Word Problems. Check your understanding of how to calculate the area of a circle.