"Estimating Area" is section 4 of chapter 5, "Measurement of Circles". The learning goal was to figure out a good way to estimate the area of a circle.

We started by stating what we know about circumference and area. We stated that the circumference of a circle is its outside boundary. Circumference is measured in $latex cm$, $latex m$ or $latex km$, since it is 1-dimensional. Area is the space inside the shape, and it is measured in $latex cm^2$, $latex m^2$ or $latex km^2$, since it is 2-dimensional.

Next, we talked about why it is important to use $latex cm^2$ as units for every different type of surface area, from squares to rectangles to circles to the surface area of a complex 3D shape, like that of a car. We reasoned that by measuring all these different surfaces using the same units, it makes it easier to compare them.

Finally, though I don't have pictures, we took a circle, cut it up into 8 pieces, and organized it into the shape of a parallelogram. In this way, we were able to determine that the area of a circle is given by the formula, $latex A_{circle} = \pi r^2$.

Section 5.4: Estimating Area

These are the notes taken with Mrs. Kelley's homeroom class. File 2015-09-17, 12 55 52 PM

Section 5.4: Estimating Area

This is the same activity, but done with Mr. Barr's homeroom.File 2015-09-17, 12 56 06 PM

Support Questions

These are the support questions we did to help check our understanding.File 2015-09-17, 12 55 06 PM