Some simple chemistry is used to demonstrate how Fe(II) ions, formed during iron corrosion in acid aqueous solution, can reduce toxic Cr(VI) species, forming soluble Cr(III) and Fe(III) ions. These ions, in turn, can be precipitated by neutralizing the solution. The procedure provides a treatment for industrial wastewaters commonly found in…

Problem posing is a higher-order, active-learning task that is important for students to develop. This article describes a series of interdisciplinary learning activities designed to help students strengthen their problem-posing skills, which requires that students become more responsible for their learning and that faculty move to a facilitator…

Children learn from a very early age what it means to get their "fair share." Whether it is candy or birthday cake, many children successfully create equal-size groups or parts of a collection or whole but later struggle to create fair shares of multiple wholes, such as fairly sharing four pies among a family of seven. Recent research suggests…

Making problem solving a central part of teaching may be challenging to teachers who have limited experiences in learning and teaching mathematics in this way. Math Teachers' Circles were developed with the aim of establishing a "culture of problem solving" among middle school mathematics teachers. This culture could then be carried back into…

We discuss the need for devoting time in differential equations courses to modelling and the completion of the modelling process with efforts to estimate the parameters in the models using data. We estimate the parameters present in several differential equation models of chemical reactions of order n, where n = 0, 1, 2, and apply more general…

This article presents the methods, materials, and manpower required to create a strategic leadership program for promoting, sustaining, and advancing institutional significance. The functionality of the program is based on the Original Case Study Design (OCSD) methodology, in which participants are given actual college issues to investigate from a…

I argue for the inclusion of topics in high school mathematics curricula that are traditionally reserved for high achieving students preparing for mathematical contests. These include the arithmetic mean--geometric mean inequality which has many practical applications in mathematical modelling. The problem of extremalising functions of more than…

Many optimization problems can be solved without resorting to calculus. This article develops a new variational method for optimization that relies on inequalities. The method is illustrated by four examples, the last of which provides a completely algebraic solution to the problem of minimizing the time it takes a dog to retrieve a thrown ball,…

For a suitably nice, real-valued function "f" defined on an open interval containing [a,b], f(b) can be expressed as p[subscript n](b) (the nth Taylor polynomial of f centered at a) plus an error term of the (Lagrange) form f[superscript (n+1)](c)(b-a)[superscript (n+1)]/(n+1)! for some c in (a,b). This article is for those who think that not…

The title question has at least two natural answers, one "global" and one "local." Global: "when they can be made to coincide by a rigid motion of the whole plane;" local: "when there is a one-to-one distance preserving mapping of one onto the other." Self-evidently global implies local. We show that in fact these different notions lead to…

When reasoning about infinite sets, children seem to activate four categories of conceptual structures: geometric (g-structures), arithmetic (a-structures), fractal-type (f-structures), and density-type (d-structures). Students select different problem-solving strategies depending on the structure they recognize within the problem domain. They…

Separate a three-digit number into its component digits. After raising each digit to the third power and computing the sum of the cubes, determine how often the original number reappears. Modular arithmetic is used to reduce the number of potential solutions to a more manageable quantity. (Contains 4 tables.)

A particle that moves along a smooth track in a vertical plane is influenced by two forces: gravity and normal force. The force experienced by roller coaster riders is the normal force, so a natural question to ask is, what shape of the track gives a normal force of constant magnitude? Here we solve this problem. It turns out that the solution is…

In this note, we present an interesting approach to sum subseries in closed form. This approach seems to be not widely known and remains under-appreciated. Our study will lead to the discovery of results some of which have been known for a long time, some which were found only recently, as well as those which appear to be new.

One of the most difficult tasks that classroom teachers face is finding ways to reach all their students and match each student's level of mathematical readiness and performance to the skills they are required to teach. In classrooms and schools, current federal and state requirements have increased the emphasis on accountability for improved…