Addition Algorithm - Partial Sums http://www.dallassd.com/resources/parent%20Resources/PartialSums.htm
Subtraction Algorithm - Partial Differences http://www.dallassd.com/resources/parent%20Resources/PartialDifferences.htm
Multiplication Algorithm - Partial Products http://www.dallassd.com/resources/Parent%20Resources/PartialProducts.htm
Multiplication Algorithm http://www.dallassd.com/resources/Parent%20Resources/Lattice.htm
Division Algorithm http://www.dallassd.com/resources/Parent%20Resources/Divisionsubtmethod.htm
Division Algorithm http://www.dallassd.com/resources/Parent%20Resources/Divisionsubtmethodwdecimals.htm
Third Grade Content http://everydaymath.uchicago.edu/educators/3rdgradecontent.shtml