Child-Size Masterpieces - Transportation in America Paperback – May 10, 1992

I bought this step ages ago and am finally putting it together but even with the book, How to Use Child-Size Masterpieces, I'm not sure how to do the orange folder. It said double folder (which I've made before) and said something about 12 and 24 cards but this came with like five sets so I'm not sure how to divide it since a double folder would only have four sections. It also doesn't have the names printed on the postcards even though the HUCSM book said to write it on the cards in this step.

I love these postcards & the "Mommy, It's a Renoir!" program for art study. My children (ages 5-21) have all used this program, & we are very happy with it. These cards are sturdy & beautiful!