Exploring circles

Today in grade 9 we made circles out of string, measured the circumference, and measured the diameter.

We graphed diameter on the horizontal axis, and circumference on the vertical axis.

We looked at the line of best fit, calculated the slope and looked at the y intercept.

The correlation was strong, direct, linear, and positive. The slope was just more than 3, and we determined that the slope should be pi.

Some minds were blown.