I took some eggs from our ducks at home and we are incubating them in my first grade classroom. We are on day 29/30 depending on when you start counting (I have seen many different opinions on that). We have 4 that have hatched and one that has been going at it for 2 1/2 days now! None of the other 8 eggs have even externally pipped yet I was so careful to keep the temperature and humidity perfect throughout the whole incubation period! I candled the eggs a couple days before lockdown and they were all doing great and wriggling around! What could have gone wrong?? Should I give them another couple days or so? Our two drakes are a runner and a mallard. And our hens are runners, mallards, and a rouen. Do rouens take a bit longer since they are bigger ducks? Any advice would be appreciated!