The flutter kick is characterized by alternating upward and downward motion of legs with slight bending of the knees. Thus, while swimming using the flutter kick, your right leg should move upward, when your left leg moves downward. When executing the flutter kick, make sure that your feet do not rise above the surface of the water. So, your feet shouldn't make a splash when your legs are moving up and down. Thus, the legs move in a wave-like fashion that generate propulsion.
Start the exercise by resting on your back with your hand placed below the buttocks with your head up. Your hands should form a fist with the thumbs facing up. The legs should be in an elevated position with the feet 6 inches above the floor. Now, move the right leg upwards by a few inches, without raising the left leg. In the next step, lower the right leg, and at the same time, raise the left leg. Continue this alternating up-and-down movement of the legs, with the knees slightly bent and the feet 6 inches off the floor.
The starting position of flutter and scissor kick exercise is the same, i.e., lying on the back with head raised, hands below the buttocks, and legs elevated. Now, instead of raising the left or right leg a few inches up, you have to move the leg straight up, perpendicular to the floor plane. Now, lower the leg to its starting position, and while it is brought down, move the other leg up. Repeat this leg movement until you feel tired.