Last time I used it we sang the song 'Little Red Wagon' and after the first round where we bounced up and down in the wagon I brought out different vehicles to bounce in. To go better with the construction theme I added a bulldozer and a cement mixer. So, with the dump truck and pick up truck I could do the song again and have 4 verses. I could also use it with the 'Brown bear' version (like the book Brown bear, brown bear, what do you see? by Bill Martin Jr.) where you say 'blue truck, blue truck, what do you see,' then put up the next one and have the kids yell out the color or type of truck.
If I happen to get ambitious I may try to add a steam roller, bucket truck, or excavator, but we will see what kind of time there is. I always enjoy when I have something on hand that can be adapted a little to fit a new theme. And, I like being able to add to sets instead of making whole new ones. Multi-purpose flannel boards are kind of awesome.