According to your description, your child may got wandering eyes. Usually, wandering eyes are caused by the abnormality of an eye's neuromuscular control. I have read an article at AllAboutVision.com, vision therapy can used to treat wandering eye. Besides, you can also use devices. for example, a patch over the good eye that can affected eye to strengthen its muscles. Hope this helps.
That is to say your child cannot concentrate. Actually, the parents should create a relatively quiet atmosphere for the kids, so that they can stretch their imagination while playing with toils and gradually develop a higher concentration. Don't give them toils too much at one time, which can also distract them.