In 1936, Albert Einstein wrote a brief article where he suggested the possibility that a massive object acted as a lens, amplifying the brightness of a star. As time went by, this phenomenon--known as gravitational lensing--has become a powerful research tool in astrophysics. The simplest and symmetrical expression of a gravitational lens is known…

Historical accounts of trigonometry refer to the works of many Indian and Arab astronomers on the origin of the trigonometric functions as we know them now, in particular Abu al-Wafa (ca. 980 CE), who determined and named all known trigonometric functions from segments constructed on a regular circle and later on a unit circle (Moussa 2011;…

Smartphones used as tools provide opportunities for the teaching of the concepts of accuracy and precision and the mathematical concept of arctan. The accuracy and precision of a trigonometric experiment using entirely mechanical tools is compared to one using electronic tools, such as a smartphone clinometer application and a laser pointer. This…

A growing body of literature has identified quantitative and covariational reasoning as critical for secondary and undergraduate student learning, particularly for topics that require students to make sense of relationships between quantities. The present study extends this body of literature by characterizing an undergraduate precalculus…

In this article, the author describes the development and implementation of a measurement-based group activity designed to support students in understanding the connection between angle magnitude and the shape of the sine function. She explains that the benefit of this activity is that it allows students to build their trigonometric knowledge…

Many studies argue that dynamic features of the artefact Cabri may function as instruments of semiotic mediation. Our study is situated in this perspective and aims to observe the impact of the use of the technological artefact Cabri in a teaching experiment that introduces the notion of a trigonometry function, through the articulation of the…

Constructing model hot air balloons is an activity that captures the imaginations of students, enabling teachers to present required content to minds that are open to receive it. Additionally, there are few activities that lend themselves to integrating so much content across subject areas. In this article, the authors describe how they have…

Presents two ideas to help beginning mathematics teachers. The first presents a way to record and grade homework. The second suggests a manipulative to help students understand the trigonometric concept of reference angle. (MDH)

Describes an activity to study the concepts of force and gravity. Students use trigonometry to measure the height of a water balloon shot into the air by a giant slingshot by two methods. A lesson plan provides materials needed, procedures, a chart to record data, and extensions for the activity. (MDH)

Presents three teaching ideas involving (1) results of participation in the annual American Statistical Association's poster contest for students in grades K-12; (2) a variation on an annuity problem in which the contribution each year is increased by a given percentage; and (3) concrete activities to help students understand the meaning of radian…