**FEATURES** |

Making Mathematical Connections by Constructing Tetrahedra
*Jennifer Bergner, Randall Groth* A polyhedra construction project that illustrates how one activity can address several of the mathematics content standards. Directions are given for a multiple day lesson on building a large tetrahedron in groups. |

Visualizing the Domain and Range of the Composition of Functions
*Nial Neger, Michael Frame* A graphical method for visualizing compositions of functions; this method is used to find domains and ranges of compositions. Authors use examples of graphical iterations from Chaos Theory. Directions are given for teachers/students to use their graphing calculators in similar examples. |

Placing a Deck of Cards in Order
*Mark Yates* Finding the minimum number of moves to order a deck of cards by placing them in suits, but not necessarily in order. Students gather data and create equations to model their patterns in algebra or statistics. |

That Ubiquitous Sum: 1 + 2 + 3 + • • • + n
*Stanley Bezuszka, Margaret Kenney* How the arithmetic series 1 + 2 + 3 + . . . + n is pervasive in mathematical contexts as a powerful problem-solving tool. Algebra students solve the problem with multiple approaches including geometric and creating general equations. Authors discuss the work of Cantor and Gauss in relation to the series. |