In 3rd Grade your children build on their earlier work with shapes by understanding the concept of area. Students learn that area is a measurable attribute and they start their measuring using unit squares.
Talk with your children about different sized shapes. Ensure you children know what is meant by "larger area" e.g. the space taken up by a shape. Ask which is the largest or the smallest or ask which takes up most space.
Have your children try this worksheet to check their understanding of "largest" and "smallest".
Note: The two activity worksheets below required unit squares to be printed and cut out. If you have card or stiff paper then this will make manipulating these much easier.
Guide your children through the "hands-on"activity in the first of the area worksheets to start finding the area of 2-dimensional shapes.
This worksheet involves cutting a 12 x 1 unit square strip into lengths of 6, 4, and 3 and using the cut-up strips to make rectangles. Discuss the lengths of the sides with your children and, importantly, why the rectangles are of equal area.
Introduce the idea of a unit of measurement. Encourage your children to move on from referring to the number of squares to referring to the number of square units. Be precise when talking about and writing area measurements. e.g. "the area is 12 square units" as opposed to just "the area is 12"
Stress the importance to your children of using units of the same size when measuring and comparing the areas of different objects. Remind them also of the importance of placing the square units without gaps or overlaps.
Work through this finding area activity worksheet to help your children understand more about units of measurement.
In this worksheet to find area your children will use a ruler to mark increments every centimeter and then draw square centimeters to find the area of various rectangles.
You might find this 5-page document has blank grids at various spacing (including centimeters, inches, and quarter inches).