The difference between...

Sorry, it's another goldfinch, but I rarely see them on the ground. This little beauty didn't mind me standing right next to the window.
I probably shouldn't admit that this was during a maths lesson! But we had all been temporarily distracted from negative numbers by the very positive image of a great tit visiting the bird box put up only yesterday afternoon.
We soon got our heads down again. Down into the negatives, that is.