Number and Number Sense

Interactive Hundred Grid with different counters/markers

http://www.amblesideprimary.com/ambleweb/mentalmaths/countersquare.html

Interactive Hundred Grid that can be highlighted in different colors

http://www.apples4theteacher.com/math/games/100-number-chart-one.html#interactive100chart

Computation and Estimation

Virtual Version of Cuisenaire Rods

http://arcytech.org/java/integers/integers.html

Virtual Base 10 blocks

http://nlvm.usu.edu/EN/NAV/category_g_2_t_1.html

Geometry and Measurement

Interactive Geometry Activities

http://www.shodor.org/curriculum/subject.php

Patterns, Functions and Algebra

Virtual Attribute Blocks

http://nlvm.usu.edu/en/nav/frames_asid_270_g_1_t_3.html 

Pattern Games under section 2.2.2

http://www.internet4classrooms.com/skills_2nd_math.htm#algebra

Math Tools for Teachers

Lessons using Algeblocks

http://www.ttac.vt.edu/math_tools.html

Lois Williams from the Virginia Department of Education has her video presentations on Algeblocks available at the site listed below:

http://www.vdoe.whro.org/A_Blocks05/index.html