Pre-Algebra:
http://www.glencoe.com/sec/math/studytools/prealglblr.shtml
http://www.glencoe.com/sec/math/studytools/prealgchaprev.shtml

Algebra I:
http://www.glencoe.com/sec/math/studytools/alg1chaprev.shtml
http://www.glencoe.com/sec/math/studytools/alg1lblr.shtml

Algebra II:
http://www.glencoe.com/sec/math/studytools/alg2chaprev.shtml
http://www.glencoe.com/sec/math/studytools/alg2lblr.shtml
http://www.kraftwrk.com/resources/matrixmath/tut_main.htm
http://www.maths.surrey.ac.uk/interactivemaths/emmaspages/Matrix2.html