The park’s Junior Ranger Program is free, and it’s a good way to keep kids focused as they participate in hikes or activities to earn a certificate and badge. Five different awards and program levels target age groups from 4–14. Required activities include at least one ranger program. On the South Rim , you can pick up a Junior Ranger Activity Booklet at the Visitors Center at Canyon View Information Plaza , Yavapai Observation Station , Park Headquarters , or Tusayan Museum . On the North Rim , Junior Ranger booklets are available at the visitors center. There’s also a Junior Ranger program specifically for Phantom Ranch .
Many canyon trails have fine day-hike destinations suitable for kids, but if trails leading into the canyon are too steep for your parental peace of mind, stick to gentler trails above the rim. On the South Rim, some paved portions of the Rim Trail  are manageable for strollers. On the North Rim, the Uncle Jim , Transept , Cliff Springs , and Widforss Trails  follow the rim or head through the forest, especially good choices for hiking with kids age four and older.
Along park trails, you’ll find many opportunities to introduce your kids to nature: wildlife-viewing, fire ecology, and identifying birds or wildflowers. (Remember: It’s illegal to pick plants or collect seeds within the park.) If you’d rather turn the nature talk over to an expert, rangers guide short hikes several times a day on both rims. Look for family-friendly walks in the ranger program schedule, usually listed in the first few pages of The Guide,  the park’s newspaper.
Most of the park’s free ranger programs are suitable for kids, and any ranger program fulfills the activity requirement for the Junior Ranger Program. Some programs are specifically family oriented, including fossil walks, story times, and games. Look for the Family Fun symbol on the program schedule in The Guide.  Children must be supervised and accompanied by a parent.
Naturalists with the Grand Canyon Field Institute (GCFI, 886/471-4435, www.grandcanyon.org/fieldinstitute ) hold single-day family classes called “Meet the Canyon.” You can pick a date by calling the GCFI. Private, customized outings may also be available.
Xanterra Parks & Resorts (928/638-2525 or 928/638-2485) and the GCFI team up for twice-weekly Learning & Lodging programs that combine accommodations, meals, and naturalist-led walks. Children must be 10 or older and accompanied by an adult.
The Grand Canyon Railway (928/635-2461, 928/773-0147 or 800/843-8724) has daily departures between Williams and Grand Canyon Depot. Most air-tour companies  offer discounts for children on scenic flights and on tour packages combining flights with land tours or boat trips.
Mule trips to Phantom Ranch  (888/297-2757) or the Abyss  don’t have an age limit but require that all riders be at least 4 feet, 7 inches tall. Children 15 and younger must be accompanied by an adult on mule trips.
On the North Rim, hour-long mule tours (435/679-8665) are suitable for kids as young as seven years. Wagon rides and horseback tours are offered by concessionaires in neighboring Kaibab National Forest (near North Rim, 435/644-8150; near South Rim, 928/638-2891 or 928/638-3105). Colorado River Discovery (928/645-9175 or 888/522-6644, www.raftthecanyon.com ) leads half-day motorized, smooth-water floats from Glen Canyon Dam to Lees Ferry, suitable for children as young as four.
On the South Rim, the Kaibab Learning Center (928/638-6333, 7:30 a.m.–5:30 p.m. Mon.–Fri.) offers day care services for infants and children up to 12 years old, when spaces are available. Immunization records must be provided.