I am hatching chicks for the first time in my classroom. I am on Day 9 and candled 4 eggs this morning and am worried about my hatch rate. I am attaching the photos of the 4 eggs I candled- I only see veins in the last two photos (Egg 4) and blood rings in the rest? I'm feeling pretty disappointed. Any information anyone could give me would be super helpful! THANK YOU!! 
EGG 1
EGG 2
EGG 3
EGG 4

EGG 1
EGG 2
EGG 3
EGG 4