problem Golden eggs Age 16 to 18 Challenge level Find a connection between the shape of a special ellipse and an infinite string of nested square roots.
problem Cocked hat Age 16 to 18 Challenge level Sketch the graphs for this implicitly defined family of functions.
problem Plus or minus Age 16 to 18 Challenge level Make and prove a conjecture about the value of the product of the Fibonacci numbers $F_{n+1}F_{n-1}$.
problem Resistance Age 16 to 18 Challenge level Find the equation from which to calculate the resistance of an infinite network of resistances.
problem Mega quadratic equations Age 14 to 18 Challenge level What do you get when you raise a quadratic to the power of a quadratic?
problem A third of the area Age 14 to 16 Challenge level The area of the small square is $\frac13$ of the area of the large square. What is $\frac xy$?
interactivity Proof sorter - quadratic equation This is an interactivity in which you have to sort the steps in the completion of the square into the correct order to prove the formula for the solutions of quadratic equations.
article Continued fractions ii In this article we show that every whole number can be written as a continued fraction of the form k/(1+k/(1+k/...)).
article Golden mathematics A voyage of discovery through a sequence of challenges exploring properties of the Golden Ratio and Fibonacci numbers.