# Friday Five for June 24

The Friday Five is still a bit disoriented by that Messi goal this week. A scattered mind means an unrelated—but no less delightful for it—grab bag of activities.

## Parabola Slalom

This activity from the mind of Paul Jorgens may just be the Friday Five’s favorite new activity in quite a while. Go, algebra teachers, go! Play parabola slalom and report back your successes, struggles, and insights! And also the Friday Five expects to see some new non-parabolic slalom challenges from the masses. If you build ‘em, ping us on Twitter and share the wealth, OK?

## Array

This is a graph, not an activity. But it’s a graph that we have seen multiple requests for over time. If you have ever wondered, How do I build adjustable rows and columns? then this graph has your technique. Thanks to Michael Pershan for prompting this, and Luke Walsh for executing.

## Calendar Arithmetic

Are you a π day connoisseur? Were you delighted by the recent Palindrome Week (coming back in July, 2017…US only!)? Then Calendar Math is for you. Take the numbers in today’s date, (month and day of month): Can you combine them to get the year? Can you do it a different way? Can you do it in a way that your classmate’s won’t have considered? Is it always possible, no matter the date?

## Finding Domain and Range

There are a number of domain and range activities in the Desmos database. Here’s a nice one for practice. It assumes your students have encountered these terms, and gives them interesting cases to consider. They go both directions—specifying the domain and range of given relations, and creating relations with specified domain and range.

## Sketchy Derivatives

The Friday Five cannot get enough of sketch. So useful; so fun. (And now with colors and a line segment tool!) Here students sketch derivatives of given functions, then functions whose derivative is the given function. Sketch lets you collect your students’ informal understanding, and share it back out for discussion.

May all your math in the coming week be as delightful and surprising as a Lionel Messi free kick!