When we think about circles, two important ideas come to mind: circumference and area.

1. Circumference: This is the distance all the way around the circle. You can find it using this formula:
   $C = 2\pi r$
   Here, $r$ is the radius, which is the distance from the center of the circle to the edge. For example, if a circle has a radius of 3 cm, you can find the circumference like this:
   $C = 2\pi(3) = 6\pi \approx 18.85 \text{ cm}$
   So, the distance around our circle is about 18.85 cm.

2. Area: This tells us how much space is inside the circle. To calculate the area, we use this formula:
   $A = \pi r^2$
   Using the same circle with a radius of 3 cm, we can find the area:
   $A = \pi(3^2) = 9\pi \approx 28.27 \text{ cm}²$
   This means the space inside the circle is about 28.27 cm².

By learning about these two parts—circumference and area—students can better understand what a circle is all about!