On a dark gray blackboard, many mathematical formulas are written in chalkOn a dark gray blackboard, many mathematical formulas are written in chalk
A green sprout makes its way through a crack in the boardsA green sprout makes its way through a crack in the boards
Aircraft carrier with airplanes and turntables on boardAircraft carrier with airplanes and turntables on board
A flowing waterfall on the background of autumn multicolored leavesA flowing waterfall on the background of autumn multicolored leaves