**FEATURES** |

What's on Your Radar Screen? Distance-Rate-Time Problems from NASA
*Gregory Condon, Miriam Landesman, Agnes Calasanz-Kaiser* NASA's FlyBy Math -- a series of six standards-based distance-rate-time investigations in air traffic control. Sixth-grade students—acting as pilots, air traffic controllers, and NASA scientists—conduct an experiment and then use multiple mathematical representations to analyze and solve a problem involving two planes flying on intersecting routes. Includes links to online videos, questions and problems for students, and examples of student work. |

Using Thought Bubble Pictures to Assess Students' Feelings about Mathematics
*Debby Zambo, Ron Zambo* How to use and evaluate "thought bubble pictures" to uncover students' feelings about mathematics. Includes blank "thought bubble pictures" for students to fill in faces and words, sample student work, and tables to use for analysis of the pictures. |

Understanding the Properties of Arithmetic: A Prerequisite for Success in Algebra
*Margaret Tent* The role of the commutative, associative, distributive, and identity properties of addition and multiplication in preparing children for future success in algebra. Includes examples of models that can be used to explain and represent each property. |

The Revolution in Arithmetic
*William Brownell* This article is reprinted from Arithmetic Teacher, February 1954. It outlines the evolution of arithmetic in schools from the 1900's to the 1950's. |

Do You Understand Your Algorithms?
*Jamar Pickreign, Robert Rogers* Relationships between the development of an understanding of algorithms and algebraic thinking. It also provides some sample activities for middle school teachers of mathematics to help promote students' algebraic thinking. |

Selecting High-Quality Mathematics Textbooks
*James Tarr, Barbara Reys, David Barker, Rick Billstein* A general framework for reviewing mathematics textbooks, including a set of quality considerations organized around three key dimensions – Mathematics Content Emphasis, Instructional Focus, and Teacher Support. The quality considerations are intended to stimulate discussion of issues surrounding textbook selection. |