This post explains and give practice opportunities related to TEKS 6.8B:
model area formulas for parallelograms, trapezoids, and triangles by decomposing and rearranging parts of these shapes
Area formulas should be memorized but that doesn't mean students should know how to derive them. Here's how to find the formula for the area of a triangle.
Here's a video showing how to derive the area of a parallelogram.
Finally, the formula for area of a trapezoid can be represented multiple ways.
To view all the posts in this 6th grade TEKS review series, click here.