Many years ago....almost five years!...MathNEXUS included a reference to Fawn Nguyen. At that time, my purpose was to use her approach to a classroom website as a positive model for other teachers.
Now, over the intervening years, Fawn has expanded her website considerably...and showing great creativity of her part. I expected such!
A big part of mathematics is exploring visual patterns, and trying to represent them algebraically. Consider Fawn's offering of Visual Patterns....160+ of them. Some will push your students (and you).
The web site VisualPatterns.org was started by Fawn Nguyen in late 2013. Other people have made contributions...and she welcomes your contributions as well!
Also browse the Gallery section, as it includes some visual patterns submitted by students as well as some relevant commentary by other mathematics teachers.
Great resource Fawn! (and thanks to M.J. of Bellingham for sending me this resource link.)