At 7 months Will is able to sit without support, but his balance is still precarious and he falls over from time-to-time even when playing quietly. Here you see Will falling over, but as his fall is contained by the foam block, he is able to right himself again.
With the support of the raised surface provided by the foam blocks, Will is able to rotate to the left and the right and reach across the body.
Will sitting 7 months 2 weeks
Will's sitting abilities at 7 month 2 weeks illustrate all the characteristics of sitting seen in infants who have recently learned to sit independently.
He is able to maintain his balance as long as he stays with his COM aligned over his base.
When he reaches sideways and props on his arm, he is not able to come upright again, instead moves to prone kneeling and then to prone.
If provided with a changed environment - in this case a 10 cm high foam block to his right and left, Will is able to explore a range of different options for reaching and sitting.
Although he still has difficulties moving from a sideways leaning sitting position, at least when he does topple over backwards, his fall is broken by the foam blocks. Notice that Will manages to control his head as he moves backwards.
Will 7m 2w sitting
Will 7m 2w sitting
Will's balance in sitting has improved with practice.
He now displays fast and adequate balance responses, which means that he falls over less often.
He reaches far forwards and comes erect again, and is able to turn his head and look upwards.
He is able to reach across the body to retrieve a toy, and come upright again.
Video: Will 7m 2w playing in sitting
Will 7m 2w - transition to prone
Will is also learning to move from sitting to prone kneeling but control of this action is still developing, and he moves into prone kneeling.
Bibliography
Overview and assessment
Learning to sit: an overview of sitting development
Assessment of infant sitting: a task based approach
Sitting at different ages and stages
Sitting 2 -3 months