Create poster for nurseries

We have 12 photos which we want to create a poster that goes on the nursery wall. This will be a free poster for schools and the aim is to promote nature and show that activities can be done just with stones ie you dont have to buy anything. The poster is only A3 and there 10 words of copy with each picture which can be very small in font size. what we want is natural design and maybe some suggestion of what it can be called