Optical challenge: Find the owls among the students

Ever wondered how much brain power we use? Our mind's abilities surprise me. 

Sometimes our minds can cure our bodies. The internet is full with things we can learn from.

Today we'll challenge our minds with optical illusions. 

This should be easy with your hawk eyes.

Find the three owls among the students immediately! 15 seconds!

The puzzle depicts a large school population. Three owls are hiding in this schoolchildren photo, but they're hard to spot.

Image below shows three owls circled. 

The first is top left, the second middle, and the third bottom right.

Christmas optical challenge:You have to try and find a Christmas stocking in nine seconds