The answer will depend on one's stride length and pace, but if one is walking, a good approximation is 2000-2500 steps per mile. Step counts decrease with increasing pace. In a study by Welk et al., 2000, the mean number of steps observed per mile for women was 1996, 1662, and 1330 for speeds of 4, 6, and 7.5 miles per hour respectively. For men the mean step counts per mile were 1875, 1605, and 1307 for the same respective speeds. Step counts for all speeds were negatively related to height, weight, leg length, and stride length and were positively related to body fatness.
If you are working with children you can expect their step counts to be higher based on the fact that they aren't as tall and their legs aren't as long as adults. You could easily have your students find out how many steps that they take per mile by having them walk a mile and count their steps. They could also run a mile and count their steps and then compare their "walk a mile" and "run a mile" step counts. You might even have them predict their step counts before they actually do it.-Teresa Vollenweider, Fitness & Pedometer Expert
References
Welk, G. J., Differding, J. A., Thompson, R. W., Balir, S. N., Dziura, J., & Hart, P. (2000). The utility of the Digi-Walker step counter to access daily physical activity patterns. MEDICINE AND SCIENCE IN SPORT AND EXERCISE, 32(9), S481-S488.
