Many people have a full side split as a desired benchmark for improving their flexibility. This exercise is my favourite initial progression when working towards better flexibility in the inner thigh.
Description
Position yourself along a bare wall so that you lie on your back with your bottom towards the wall and your legs and feet facing up the wall. Then gently spread your legs apart while keeping your knees straight. Once you have settled in this position and made sure that your knees are straight, focus on gently tilting your pelvis forwards so that your lower back arches away from the floor. You can also try to rotate your toes and kneecaps down towards the floor to increase the intensity of the stretch.
Dosage
Work your way up to 60 sec and repeat 3 times per day for best result.