# Friday Five for March 25

Many people around the world celebrate Easter this weekend. A much smaller number of people celebrate the arrival of sale-priced Peeps, which are inexpensively obtained only after the holiday, to be used for the purposes of mathematics. We have at least one of these latter types on the teaching faculty here at Desmos, so be sure to tweet us (or maybe just him) if you find an especially good deal!

In the meantime, if you’re not on spring break next week (we sure aren’t!), we have some great stuff you might consider working into your lesson plans. Science (!), logarithms, geometry and modeling—all making up your Friday Five.

## Polygraph: Phases and Mixtures

JR Ginex-Orinion, who tweets at @gochemonline, brings us a chemistry teacher’s twist on Polygraph. Of course this sort of off-label usage is endorsed and encouraged.

## Logarithmic Graphs

Speaking of chemistry, identifying the base (heh), and then translating the graph of a logarithmic function is something kids don’t get to play around with very often. Until now! Mr. Michalak focuses students’ attention on the value of the function when x=1, treating this point a bit like we do the vertex of a parabola.

Click on through, give it a try, and maybe gain a new perspective on logarithms.

## Parallelograms in the Coordinate Plane.

Are these four points the vertices of a parallelogram or are they not? How do you know? How could you check? What additional information or representations would be useful to have in order to check with precision? Teacher Jared leads students—in proud Desmos style—through a progression from intuition to formal structures, and on to generalization. Sharp, tight coordinate geometry right here.

## Are People Waiting to get Married? and College Tuition

We wrap up with two Michael Fenton specials. In the first, students analyze and discuss the long-term trends of average age of marriage for men and for women in the US. (Is there modeling in this activity? you’re asking yourself. You’d better believe there is!) In the second activity, it’s the long-term trends in college tuition at different types of institutions that is up for examination.