# Think Globally and Locally, Mathematically

Student Explorations in Mathematics, formerly known as Student Math Notes, is an official publication of the National Council of Teachers of Mathematics (NCTM) and is intended as a resource for grades 5-10 students, teachers, and teacher educators. Each issue develops a single mathematical theme or concept in such a way that fifth grade students can understand the first one or two pages and high school students will be challenged by the last page. The content and style of the notes are intended to interest students in the power and beauty of mathematics and to introduce teachers to some of the challenging areas of mathematics that are within the reach of their students.

The teacher version includes additional information on world poverty as well as instructional ideas to facilitate classroom discourse. The student guides are available for free download (see below) but the teacher’s guides are only available with NCTM membership.

In the following activities from the May 2011 and September 2011 issues of the magazine, students use histograms and make comparisons between different country groups, then create graphs that compare these differences in many ways and consider how each of these displays might be used. In part 2, students consider important information about world poverty by using measures of central tendency and box plots. Students analyze data and use a hands-on manipulative to interpret and understand box plots, including the connection between percentiles and quartiles.

Part 1: Hunger at Home and Abroad (May 2011)

Part 2: Poverty at Home and Abroad (September 2011)

# Percentages

Mastering the concept of percentage and learning to solve practical problems involving percents are goals of the NCTM Principals and Standards for School Mathematics Number and Operations Standard for middle grades students. Here are several approaches to reaching those goals.

Figure This! Math Challenges for Families
Created for students in grades 6 to 8, the site offers some intriguing percentage problems. You might try these with your class: Popcorn, Majority Vote, and Perplexing Percentages.

Percentages
This virtual manipulative helps students see the relationships among the three quantities involved in calculating a percent: the part, the whole, and the percent. It shows the relationship graphically but also displays the calculations involved.

Grid and Percent It
This lesson focuses on the basic concept of percent: parts per hundred. Students use a 10 × 10 grid, which is a common model for visualizing percents, extended to solve various kinds of percent problems. A worksheet of grids and all steps in a complete lesson plan are given.

Saloon Snap
Students try their hand at matching fractions with decimals and percentages. When they see a Snap, they ring the bell quickly before Fast Fingers Malcolm does!

Percent Shopping
Toys on sale! Students choose which toys to buy, figure the total price, then find the discounted price. At a higher level, they find the percent discount when the original price and the sale price are known. Feedback is immediate and help available.