Shape A, B and C all have 4 sides and 4 corners, but can you see that Shape D has 5 sides and 5 corners. This is the odd one out. A shape with 5 sides and 5 corners is called a pentagon.

The Pentagon's distinctive five-sided shape wasn't an arbitrary decision. Initially, it was designed to fit a plot of land near Arlington Cemetery, which was bordered by five roads. Though the ...