Walking up to the edge of the Grand Canyon that July day was as suspenseful as creeping downstairs on Christmas morning. Our group of nine children and their grandparents all obeyed the tour guide: "Walk looking down. And don't look up till I say so." But when the guide said, "Now!" my husband, Dave, and I were more focused on Ben, our 12-year-old grandson, than on the magnificent canyon suddenly spread out before us.

We were on Day Four of a five-day Road Scholar tour for grandparents and grandchildren, which also included rafting on the Colorado River. We had heard raves from friends about similar Road Scholar "intergenerational" trips that provided a rare bonding and learning experience by cutting out the middlemen: the parents.

The trick for us had been finding a free week in Ben's hectic summer sports schedule. I confess that my second or third thought upon hearing that he had broken his arm skateboarding was that he might be sidelined from his competitive golf and soccer long enough to travel with us. And he was.

We chose the Grand Canyon trip from a list of more than 60 reasonably priced grandparent-grandchild possibilities, from Hawaii to Yellowstone, Chicago to Chincoteague. Road Scholar - the "lifelong learning" tour group formerly known as Elderhostel and mostly aimed at older adults - expands its intergenerational tour listings by 10 percent each year.

They accept kids 8 and older for most trips, although a handful of tours will take those as young as 6, even to camp in the Adirondacks. There are physically active trips that focus on snorkeling or kayaking or even flight instruction, as well as some to Disney World or dedicated to topics of study, such as robotics and archaeology. For kids 10 and older, there even are a few foreign destinations, such as Switzerland for hiking.

The course description of five days in Arizona for kids 9 to 12, including the rafting and the canyon, sold Ben, us, and his parents. My husband and I hadn't seen the Grand Canyon ourselves for more than 40 years, and, for Ben, it would be a real change from his Washington scene. Five days sounded perfect.

When we gathered on a Sunday afternoon at the base hotel, a modest La Quinta in Flagstaff, we met our fellow oldsters from across the country (two other couples, the rest single grandmothers), and discovered we were the only first-time Road Scholars. All the others had taken the same kids or their siblings to other destinations. Some, like us, were with grandchildren they are lucky enough to live close to, but for several, it was a rare chance to share time with children they don't often see.

The four full days of the program had a rhythm. Tuesday and Thursday had us on the road for quite a few hours and presented the greatest adventures. Monday and Wednesday were more restful - plenty of activities but little traveling.

On Monday, we drove just a couple of miles to Northern Arizona University's Challenge Course of 30-foot-high ladders and zip-lines.

The goal was to have the grandchildren get acquainted and comfortable, and by that evening, after a group dinner, they all headed for the first of four nights in the hotel pool. Bonding accomplished.

Rafting on a calm section of the Colorado was Tuesday's experience. After a van ride about three hours north to the enormous dam at Lake Powell, we boarded a large, permanently inflated raft and spent two hours in the thrall of a magnetic young lord of the river, Easy Johnson, who piloted with one hand and pointed out landmarks with the other, captivating the kids with his tales.

A word about the special challenges with an intergenerational crowd. Our group - which was in line with Road Scholar's average grandparent age range of 68 to 74 - brought with it a few of the health concerns predictable for that older set, and there were issues among the younger ones, too, such as homesickness. Our group leader, Joanna Joseph, has seen it all in her 20-plus years doing these trips, but she was unfailingly enthusiastic.

And what about the bonding across the generations? The chance to share challenging adventures with our grandson and watch him enjoying new friends was a moving experience. For all of us, it was mostly a week of light-touch discipline, with just an occasional admonition from one or two grandmothers maybe overdoing the in-loco-parentis thing.

The headline trip, on the refurbished 1950s cars of the Grand Canyon Railway, took us north from Williams (a short drive from our base in Flagstaff) to the canyon. It was our last full day, so the kids knew one another well.

That moment at the canyon rim, when we all kept our eyes on the ground as we walked the last dozen yards to the edge, was followed by an hour-long hike partway down the easily navigated Bright Angel trail, where Joanna pointed out all the geological layers we had studied the day before in a classroom presentation at the hotel.

After three-plus hours, we scrambled back onto the Grand Canyon Railway. While the kids examined the woven leather bracelets they had snared at the Hopi House trading post at the rim, the grown-ups relaxed. That is, until the railway's masked Cataract Creek Gang galloped up alongside the moving train and boarded our car, guns sort of blazing (a regular photo-op stunt).

But after all this talk of intergenerational sharing, there was a telling moment. A Cataract Creek gangster, guitar in hand, struck up some Kingston Trio classics of the early '60s. As all of us grandparents belted out that all-time great train song, "M.T.A." - "Well did he ever return? No he never returned, and his fate is still unlearned" - the kids turned to their smartphones.

For information on Road Scholar Intergenerational Tours, go to www.roadscholar.org.