Absolutely have to recommend Paul Lockhart's Measurement [1]! Journey Through Genius is a great book as well. [1] http://www.hup.harvard.edu/catalog.php?isbn=9

Absolutely have to recommend Paul Lockhart's Measurement [1]! Journey Through Genius is a great book as well. [1] http://www.hup.harvard.edu/catalog.php?isbn=9780674057555 http://www.hup.harvard.edu/catalog.php?isbn=9780674057555