New adventures in travel are opening to more and more older Americans, who are living healthy lives well into their seventies and eighties, and one such adventure is taking a grandchild on a cruise or tour abroad us. I think every grandparent should try it -- at least once, as I did recently -- not so much for the education of the grandchild but for the education of the grandparent.

I took my 12-year-old grandson on an extended European tour and cruise that included Greece and its islands, Israel, Turkey, Cyprus and Egypt. We left home as soon as school permitted, seen off by friends and tearful parents who had never before been parted from their only chick for so long. I am not sure what he learned on our trip, but I learned a great deal.

Before you set off, two very essential matters should be discussed and agreed upon by all parties -- grandparents, parents and the child. One is a clear transfer of parental authority to the grandparents for the duration of the trip. The second is the child's spending money and the appropriate way of rationing it to last. This advice will save indulgent grandparents many additional expenditures when they can't say "no" to the poor child gazing longingly at giant pretzels (and lots of other things) after he or she has spent every cent the very first week.

For our adventure, I booked two escorted tours with a break in Amsterdam between them. Our expectation was that there would be youngsters my grandson's age on them. Fortunately, on the first tour this was the case. One family had a son of the same age and a slightly younger female cousin. The children were inseparable, keeping each other entertained. The second tour was supposed to have two children and a grandparent also, but they canceled out. On the ship there were numerous children, all of them seeming to speak different languages, which didn't hinder their activities a bit.

I quickly learned that the tour guides are of invaluable help since your charge will happily listen to anyone but you. The first guide was male, quite adept with youngsters and forceful when necessary: "Boys, the revolving door is not a toy," and "Pushing all of the buttons in the elevator is very naughty." The female tour guide in Greece on the second tour was very knowledgeable about classic ruins, and she took a real interest in my grandson.

The first day of the trip, my grandson lost his trip log in which he was supposed to write each day. This was just the first of many items lost, due primarily to the problem of getting him up in the morning and getting the suitcases out in the hall for early pickup.

As for the log, I wondered later what he would have written anyway, after watching him look at magazines and play seat games when traveling through the Alps and hearing him refuse to go to some of those "boring" museums. When we had returned, I asked his parents what he had said about the trip. Well, they answered, not much, "but you should hear him talking about it to his friends. So something must have impressed him."

On both tours, I heard from all sides, "Oh, you are so lucky to have such a nice grandson to help you and be company." He heard, "How lucky you are to have such a nice (generous, kind, etc.) grandmother to take you on such a wonderful trip." Meanwhile, we often were locked in a life-or-death struggle over: money, bedtime, eating unfamiliar foods, taking a bath and drinking too many Cokes. If I remonstrated publicly with him about anything, I got reporving looks, hard eyes and murmurs from other grandparents who didn't bring their grandchildren on the trip.

On the other hand, his presence was often most welcome. The first time we were overcharged in a restaurant, I picked up the bill and was about to speak to the waiter. "Let me," said my grandson, reaching for the bill. He took the bill, went up to the cashier's desk and after some moments returned not only with a big smile -- and the money -- but also with a candy bar given him by owner.

I learned that it is difficult to keep up with a 12-year-old -- both in activities and moods. He was a little boy when riding camels, donkeys and horse carts but an adult when it came to detecting overcharges in restaurant bills. One minute he could be very helpful -- "Let me carry this, Nana" -- and the very next minute he didn't care for his seniors, in fact found us nuisances.

He could be very good at coping with the different new currencies we used every day or so -- even helping some of the others on the tour with their money problems -- and then childishly, he wouldn't go to bed at night and wouldn't get up in the morning. He helped search for elderly tour members who went out for a walk and got lost, but became bored, and was loud about it, when there was free time and no planned activity.

The energy and climbing ability of the young seem inexhaustible; just watchind him exhausted me. However, as long as activities were physical -- climbing up to Neuschwanstein (the "Fairy Castle" in Bavaria); climbing the Acropolis in Athens; walking (or running) around old Salzburg in Austria -- he was fine. But free days were awful.

After I discovered that he had my good sense of location and direction, I felt I could let him explore on his own while I relaxed. He rode all over Amsterdam on a tram pass and took several rides on the Munich subway. I always checked him out first on the name and location of our hotel, and he pleased me by always returning when he was expected to.

I learned that my grandson had quite a sense of drama, too. In Bethlehem, a vendor was selling post cards -- first 20, then 20, and finally, on the bus, 40 for a dollar. I said, "It's a bargain," and gave my grandson a dollar to pay the vendor. Suddenly, in that high, rather shrill voice of the young, he said, "There are only 39 here." The vendor, anxious to sell more cards, said, "Perhaps you counted wrong," meanwhile moving quickly toward the exit.

"There are still only 39," my grandson repeated loudly, while I tried shushing him. After all, 39 was a bargain. The vendor then gave up, passed another card back and said, "Give the boy his card," to my grandson's satisfaction.

On our cruise ship, aware that the older people at our table didn't like goat anything, my grandson spoke up clearly while we were eating our Greek salads to ask, "Nana, feta cheese is goat cheese, isn't it?" This caused the others to say "ugh" and not eat the cheese they previously had enjoyed. Then he said to them, "Can I please have your feta cheese?"

All in all, I was kept off-balance, but an occasional "I love you, Nana" made up for the rough times.

And on the flight home, seeing a very tired child stretched out sleeping on the seat, a child who had spent hours looking for a Swiss army knife for his father and who had lugged a pair of wooden shoes for his mother in his carry-on bag for most of the trip, I reflected on the kind of a trip we were concluding. It was a very interesting, educational, exciting, aggravating, wonderful, disturbing, frustrating and exhausting experience -- one every grandparent, I think, should have.