I teach a cardio dance class indoors and I can't give them an accurate calorie count when class ends. The only choice is on the Apple Watch is "other" and I know the class burns 600 calories in an hour, but my watch only shows 250-350 burned. ???

I use my Apple Watch all day long and when I teach a cardio dance class, the calorie count is MUCH lower than other devices. Why is the watch not calculating my calorie count accurately? The ladies like to know calorie burn when class is over and I can't give it to them using my Apple Watch. Other people in that class that wear the watch says their count isn't accurate too. We usually burn about 600+ calories and I'll be lucky if mine registers 350. What could be wrong? thanks!