Infants and children must have good posture while laying down, sitting or standing so they have a good foundational base from which to move their arms and manipulate objects as well as attend and learn at school. If a child has to concentrate on holding up their body, this will take away from their ability to grasp and manipulate objects and concentrate and learn at school.
Therefore, it is critical for babies and children to be well supported at their chairs and tables at home, daycares and schools during feeding, reading, writing and learning tasks.
If a child is unable to maintain good posture while sitting in their chairs at home or school, it’s important to consider whether these difficulties are contributed to by poor balance, body awareness, trunk and upper body strength, or sensory processing difficulties.
Here is a great article which describes how a child should be sitting in their chair, alternate sitting positions, and ideas for movement breaks. Do share with teachers, family and friends.