# Your Friday Five for February 19th

This week we have circles, reflections, two activities about velocity and a winking boy.

## Winking Boy

Andrew Stadel and Chris Shore bring you this graphing challenge; a simplified Desman in which students try to match the image by graphing linear equations and (optionally) inequalities. Any student who can graph a line can make satisfying progress on Winking Boy.

## Who Finishes First?

Desmos’s own Michael Fenton has two of this week’s activities. In the first, he offers you a little more calculus. You see velocity graphs. One person starts out slowly, but ends up going faster; does that person overtake the other? Who Finishes First? challenges students to find position based on graphs of velocity.

## The Need for Speed

Mr. Fenton’s second activity this week also has students modeling velocity over time, but in this one, students consider speed on its own merits, so this one is aimed at algebra 1 students. If you know how quickly a car accelerates to 60 mph, can you predict how quickly it will get to 180 mph?

## Measuring Circles

Kate Nowak offers circumference of a circle as an example of a proportional relationship, thereby working on at least two important Common Core State Standards at for grade 7.

## Reflections

Cathy Yenca (whom you may know as Mathy Cathy) has students reflecting simple polygons over the x-axis, the y-axis, and the line y=x. Great coordinate place work for eighth graders!