While at my computer I heard Jack in the lounge call Luke over and tell him he was going to read Mighty Machines to him. After hearing him 'read' for a bit I realised that what he was saying was pretty special and I started typing it down. This is what I managed to capture (of about 15 similar statements):

Diggers are really strong for you.and they help you dig

Bulldozers are really big for you They push up all the roads

Plane-trucks are really good for you. They help you carry plane wings

Graders are really good for you they push up all the roads

A truck's really good you they help you drive about

 I went over to look and he point to the words on the page and told me "that's the word - that's what it says". The words he pointed to were not similar to what he was saying but he certainly was telling me he was reading them.  The picture of a 'plane-truck' was a truck with a plane wing on it's trailer