I see parallelograms everywhere

Having come to terms with the area of the triangle - and realising how parallelograms unlock the secrets of so many of our basic regular shapes ....

... it's time to look at our friend the trapezium (or trapezoid if you insist). 

Can you turn this into a parallelogram? And how does it help work out the area?

Try it out, before clicking to see more. A teacher resource is also provided at the end of the post.