A method of controlling a washing machine that includes a drum rotatably provided in a tub that receives water, at least one nozzle spraying water into the drum, a washing motor rotating the drum, and a circulation pump circulating water within the washing machine, the method including: operating the washing motor to rotate the drum in a first rotational direction while repeatedly alternating between an acceleration and a deceleration of the drum so that laundry in the drum alternates between maintaining contact with an inner surface of the drum during acceleration, and separates from the inner surface of the drum during deceleration; and operating a circulation pump motor in the circulation pump, while the drum rotates in the first rotational direction, to accelerate a pump speed of the circulation pump during the acceleration of the drum, and to decelerate the pump speed during deceleration of the drum.