(on foot) and catch one of 15 calves, put a halter on them, and drag them back to the center of the stadium. Winners are given money to purchase their own heifer or steer to show the following year. Immediately following the calf scramble is mutton busting. Five- and six-year-olds wearing protective gear try to ride a sheep across a portion of the arena. On the last night of the rodeo, the winners from each of the previous evenings compete again to see who will become grand champion. A rotating stage is then brought into the arena for the nightly concert. The majority of evenings are performances by country music singers, although several nights are dedicated to pop or rock music. The annual Go Tejano Day generally draws the largest crowds. The winner of the annual Mariachi Invitational competition is invited to perform onstage with the Tejano acts. Grounds Visitors who are not attending the rodeo and concert can purchase a lower-cost general admission ticket to gain access to all of NRG Park except the stadium. According to livestock show CEO Joel Cowley, "if we can draw people here for a concert or a carnival or a rodeo and teach them something about agriculture, it’s a win in regard to our mission." NRG Center contains AgVenture, which provides educational displays about agriculture and the origins of the food for sale at grocery stores. More than 61,000 schoolchildren visited AgVenture in 2015 on official tours. Displays include an area where attendees can see cows, pigs, and sheep give birth or see chickens hatch. There are also displays with live rabbits and honeybees. NRG Center also hosts a large vendor area. The grounds feature an area where children can do pretend farm chores and compete in races using pedal-driven tractors. There is also a petting zoo, pony and camel rides, and a full carnival and midway. Over the course of the 20-day event in 2015, visitors purchased over $23 million of food outside of the stadium. Other competitions are held throughout the three weeks at NRG Center and NRG Arena. These include open cattle shows and a paint horse competition. Children with mental and physical disabilities are invited to compete in the Lil' Rustlers Rodeo, which offers imitation rodeo events, such as riding a stick horse. Free educational seminars are available throughout the three weeks of the livestock show. They are open