First and foremost, let me apologize for the extremely poor quality of these photos.
Covered this with my students moving up to Algebra next year. We don't cover the area of a trapezoid in 6th grade.
As usual, I wanted them to understand the 'why' behind the formula.
We simply took a sheet of paper and hamburger folded it, ripped it, and shared with our neighbor (each student only needs 1/2 a sheet of paper). from there we folded it in half again, hamburger style. Then, we cut some off of the left and right sides to create a trapezoid from the rectangle.
To show that the formula of a trapezoid is 1/2 the height multiplied by the two base lengths added together, we folded the top layer of the trapezoid so that the front showed 1/2 the height. We glued it such that the portion of the trapezoid we cut off matched up with the 'flap' created from the fold.