Illustrative Mathematics
Illustrative Mathematics: 3.md the Square Counting Shortcut
This is a rectangle subdivision task; ideally instead of counting each square. students should break the letters into rectangles, multiply to find the areas, and add up the areas. Aligns with 3.MD.C: CCSS.Math.Content.3.MD.C.6 Measure...
Khan Academy
Khan Academy: Counting Unit Squares to Find Area Formula
This tutorial includes a video, questions and explanations around using unit squares to see why multiplying side-lengths can also find the area of rectangles.
Texas Instruments
Texas Instruments: Count Them Up! Using the Ti 73 Explorer
In this activity, you will investigate the areas of rectangles and squares by splitting them up into unit squares and/or half-unit squares and combining them.
Texas A&M University
Wtamu Virtual Math Lab: Intermediate Algebra
This site is a tutorial for students in algebra 2 or for those who need a refresher. The site has explanations, definitions, examples, practice problems and practice tests are found covering topics such as linear equations, graphing,...