Children present an interesting and unique user group who has in the past received minimal attention from UI/UX experts. The conventional Interaction design guidelines (for adult users) may not be applicable when designing for children.
* Development of age-appropriate content - A good example of age-appropriate content is BBC's Bitesize.
* Understanding children's mental models - Children and Adults don't have same mental models when it comes to understanding the world around them. For instance, in understanding of mathematical concepts, children might not visualize subtraction in terms of 2-1=1 but may best understand pictorial representation as follows.
* Use of appropriate language that children can understand.
*Consider ergonomic constraints that children will face while interacting with educational content. e.g font size and color contrast.
The above guidelines are by no means exhaustive but its a clear pointer that designing for children require careful planning.
Mutuvi.