Math... visually (and with tangibles!)

check out these nice visual/tangible tasks:
   Algebra Through Geometry (and visual tasks)
and
   Shape Algebra


And more here:
Task Cameos and other Iceberg Information

;)

The book for this is:

Algebra Through Geometry, by Geoff Giles (link)

And this paper:
"STUDENTS’ UNDERSTANDING OF ALGEBRAIC NOTATION:
11–15" (ref)
discusses how students (11 to 15 years old) learn algebra in relation to geometry...