what does the below rebus means?

What is the word or phrase?

What runs around the whole yard without moving?

In a university, a professor gave a set of three problems to the three brilliant students of his class. See the image for the questions.

Spot the cat in the picture below

Can you count the number of rectangles on a chessboard?

Count the number of triangles in the given picture.

Replace the (?) with the correct mathematical signs to make the expression equal to 59.

18 ? 12 ? 4 ? 5 = 59

Solve the rebus riddle in the picture below.

John is asked to stand behind Jacob and Jacob is asked to stand behind John. Both of them feel confused about it and don't know what to do?

But it is quite possible, do you know how?