Every mare is different. This is my experiences with mares.
Some mares I know just are more irritable in heat. More prone to snap their teeth at other horses, etc. My mom's mare is irritable, and "flirty." If she realizes there are boys around (even if they are geldings), she lifts up her tail, hollows her back, arches her neck, and prances. It is hilarious to watch! Some mares I know just "wink," or they act the same as they always do. I only know one mare that was really bad in heat. She was dragging her owner all over the place (even with a chain lead rope over her nose), "winking," acting like a brat undersaddle, etc. This was discovered at the horse show finals in the area. Since her owner is a beginner, they decided to put a marble-like thing in her that tricks her body into thinking she's in foal so she won't go into heat.
I hope this helps. Good luck with your report!