“Learning” starts by “imitating”. If you cannot give full attention to your younger child, let him see up close what the older is doing, as then he can watch and learn. On the other hand, if the elder is the one not getting full attention, make him aware that he is older and is relied upon and is entrusted. Please refrain from burdening him because he is older. Explain that the younger still needs your aid and that you entrust things in him because he is older and you know he is capable. Make time for cuddling, to assure him he is loved, when the younger sibling is taking a nap for example.