It is natural that you would want to keep in touch so that they would know their grandpa or grandma is thinking of them.
You can achieve this through some of these steps.
1) Since your child is busy working and establishing their own life, you can always offer to take care of their children after school.
Definitely, your offer will be appreciated by your child and your grandchild will be happy that you are willing to help them with their school work.
You can also prepare snacks for them.
2) You can send a letter or a card to your grandchild to let them know how much you miss and think of them.
3) It would be great to be part of your grandchild's every sporting event.
Sometimes their parents will forget to notify you, so you need to remind them from time to time if there are any activities in school so you can also be a part of it.
4) Calling is one of the best forms of communication especially if you live far and cannot visit them as often as you can.
Although some older grandchildren would misunderstand the constant call to be interfering, you can do this once in awhile.
5) Another way is to have your child to install any form of visual calling application in their computer so you can call them online and have a video chat.
This way, you talk and see them anytime you want.
Although it would be best to keep this brief and short, it is a way of letting your grandchild knows they can contact you anytime they want.
Grandchildren value the presence of their grandparents as they are the link to their past, as well as, their parents' past.
It is special and fun to know what they and their parents were like when they were young.
Hopefully, all grandparents get to see and communicate with their grandchildren as often as they can.
They share a special bond after all.