Prime numbers are the building blocks of numbers. This exploration of prime numbers begins with a classic tool for locating prime numbers: the sieve of Eratosthenes. We then introduce a different type of table for the process of identifying primes. The exploration looks at other patterns with prime numbers and concludes with a connection between primes and music. Exploring these prime numbers allows us to understand the combination that makes up all numbers and can open the door to many of the mysteries in math. This issue guides students through an exploration of different methods for locating prime numbers, finding patterns with prime numbers, and connecting primes and music. 

How many people are on the earth? How fast is the population growing? When will we run out of the resources needed to sustain life on our planet? Students explore these and other questions about growth in “7 Billion . . . and Growing.” They use data, measurement, unit analysis, percentages, and statistical analysis to investigate tasks about sharing earth’s resources, population growth, and growth models.

Do your students struggle with division? Many students have misunderstandings about division that relate to its definition. This exploration takes division from its definition and integer division through factoring and algebraic division using manipulatives and a variation on the standard division algorithm. It also links division, as well as factoring with integers, to algebra. This is an opportunity for students at all levels to strengthen their understanding of division and for upper-level students to explore polynomial division.

Why are we stuck in so much traffic? Can't we just build more roads? Data collected by the Texas A&M Transportation Institute shows driving time in urban areas appears to be increasing each year. In this activity, we will graph and analyze traffic data and learn about transportation issues in many of our metropolitan areas. How does your region compare to others? What options are available to ease traffic congestion in our urban areas?

This month students explore one of the “big ideas” in algebraic thinking—patterns. Students build figures that follow a pattern and describe—with words and algebraic expressions—how the figures are changing. Students then make connections between the different descriptions and the physical models. The activity also includes an introduction to discrete and continuous functions and domain and range.

As the Major League Baseball season comes to a close this fall and fans eagerly anticipate the World Series, you and your students can explore the mathematics of baseball with It's a Hit.

What's black and white with math all over? A newspaper, of course! How can you help your students apply fraction, decimal, percent, area, and ratio concepts while investigating a real-world task? Once again, the answer involves using a newspaper. A newspaper is not just for reading. Your local newspaper has many examples of real-world applications of mathematics, such as graphs, charts, sports statistics, and mathematics examples found in advertisements. In this activity, your students will flex their mathematical muscles and apply fraction, decimal, and ratio concepts to determine what percentage of your local newspaper is really news.

Capitalize on student interest in sports with this classroom-ready investigation of mean. Means are often used to compare athletes’ performances in sports. Avid student fans may know statistics for their favorite team or players, but do they know how these stats are determined? This activity explores the application of mean in baseball and basketball.

What do President James Garfield and Pythagoras have in common? They were both lovers of mathematics, and in 1876, James Garfield constructed an original proof of the Pythagorean theorem. "Constructing Pythagoras," a hands-on investigation, challenges your students to derive the Pythagorean theorem (a²+ b²= c²) using the same proof as the USA's twentieth president, James Garfield.

Since their debut on 21 December 1913 in the New York World newspaper, crosswords have intrigued and delighted puzzle solvers. Much care is taken to edit these puzzles to present challenging clues as well as to produce grids that are consistent in their visual presentation.