It's still a good idea to bring some school lessons to life by visiting historical places or museums. Some children this age would still like to hear about their roots, especially the experiences you had when you were their age that correspond to the ones they are having. Again, friends are very important to a young teen. Don't feel hurt if the child wants to take along a friend. Be prepared for sulks, sleeping late, and what you might consider inappropriate behavior with the opposite sex.
Many young teens are sexually active.
You might find your grandchildren smoking or sampling your Scotch. They might even be smoking pot rather than tobacco. If you are prepared for these occurrences before they happen, then you might not be totally shocked. In fact, think about how you will react before it happens, and you might be able to offer help rather than censure in many situations. Reading teen magazines, watching a few popular TV shows, looking through some fashion mags, male and female, will help you know what to expect.