Every enduring work is either an item of curriculum or is an item tangent to curriculum.
keywords: education, instruction, training, teaching, learning, activity

Here is the link to a discussion of this. A graph is given, and this can be taken as an exercise in straight-line construction (within a course of Algebra I). (Note that the presentation contains a glitch, namely, that although the graph is correct, the formula given is for converting from Celsius to Fahrenheit.)
keywords: Mathematics, real-world application of mathematics

Believe it or not, there is a formula for the logarithm, one that does not require arm-waving and a spiel, as the high-school version does.
Here is the link to a discussion of this approach.
keywords: Mathematics, Calculus, hyperbola, area under the curve y = 1/x