How to Tell Your Teacher You're Having Your Period
There's no need to be nervous if you get your period at school since you can discreetly tell your teacher and get things sorted. As soon as you suspect you started your period, raise your hand and ask to go to the bathroom. If your teacher says no, just say something like, “It's really urgent.” If they still say no, wait until there's a break, then approach their desk for some privacy. Say something like, “I just started my period. Can I please go to the bathroom?” If you say this they should definitely let you go. If you don't have any menstrual supplies on you, stop and see the nurse. They'll be able to give you pads, tampons, or whatever else you might need.
Request to use the restroom. Try to wait until there is a break in the class discussion or a transition between activities. Raise your hand or approach the teacher's desk and ask to visit the restroom. Do this as soon as you suspect that your period is starting so you can avoid any staining. You may need to indicate that you can't wait, as some schools limit bathroom breaks. You might say something general, such as "Excuse me, I know that we're going over important material right now, but I need to go to the restroom and it's urgent." Get specific, if necessary. Provide additional details if your teacher refuses your first bathroom break request. Approach your teacher's desk or wait until the end of class to keep this conversation private. You could explain, “I've started my period and I need to visit the restroom to take care of it.” For added protection, you can request, “Please keep this private.” They should do this anyway, but it might give you extra peace of mind to state it directly. Cover up any stains. Wrap a sweater or jacket around your waist, if you have one. If not, your teacher might let you borrow one. Know that just because you started your period does not mean that you will stain your clothes. Relax. Take a number of deep breaths as you walk to the restroom. Do a quick back stretch in the restroom. Smile. Remind yourself that women have periods and it is completely normal. Remember that this is not new. The adults around you have all dealt with periods before, in one fashion or another. They are used to these situations and will not feel weird or embarrassed about talking about your period with you. Get supplies. Check for a vending machine on the restroom wall that sells period supplies. Ask a friend for a pad or tampon. Fashion a make-shift pad by wrapping toilet paper around your hand, pressing it flat, and then placing it in your underwear. You will want to use at least ten layers. Visit the nurse. Go to his or her office and ask for a sanitary pad for period bleeding. If they have one, they will provide it to you.  If you need a few minutes to calm down and collect yourself before facing the world again, ask the nurse, “Would it be okay if I stayed here for a bit before returning?” Talk with another teacher. Approach a new teacher (maybe one that you are more comfortable with) if your first teacher was not helpful enough. Bring a period kit. Fill a small make-up bag with the following: pads, panty liners, and a change of underwear. This should help you to avoid supply emergencies in the future. Dress comfortably. Wear dark clothes if you are still concerned about blood spots. Avoid constricting clothes if you feel bloated as they will only make you more uncomfortable. Expect a bit of awkwardness. Prepare to feel a bit embarrassed, especially around any male teachers. However, remember that they will not mention what happened and quite possibly have already forgotten. Remind yourself of everything else that is going on in the classroom (doing work, taking roll) and that you are only one part of that process. Stay polite and thankful. Offer your thanks to anyone who helped you. Say, “Thank you!” or “You saved me!” or “I really appreciate what you did.” Keep it light and quick, but if you let them know how much they helped they may be more likely to help others in the future too. Stay calm. You have a plan in place in case this happens, you just need to go through the steps. Remind yourself that you are not the first person to start their period this way and you won't be the last. It may help to mentally repeat, "Calm down. Relax." Tell your teacher you're having your first period. Your teacher is there to help you. Wait until there is a pause in class and approach their desk. You might say, "This is my first period. What should I do?" They will then give you some options, such as visiting the nurse or the restroom. Talk to the school nurse if you're not comfortable talking to your teacher. Ask your teacher for a pass to visit the nurse or go in between class periods. Let her know that this is your first period and she will provide you with supplies and advice. If you are achy or hurting, let the nurse know that as well. Say, for example, "My stomach has been cramping for the past hour or so." Call a parent from the front office if you don't feel that you can talk to an adult at school. Your parent can bring supplies up to you, such as pads, and can go over what you've already planned to do in this situation. They can also remind you that it will be okay and that what you are experiencing is perfectly normal. Ask a friend who has already experienced her period what to do. Find a private place, like an empty classroom, to talk with a trusted peer. Solicit her advice on what your next steps should be and how you will feel moving forward. You might say, "I've started my first period today and I'm not sure if I can participate in gym class. What do you do?" 
Request to use the restroom. Get specific, if necessary. Cover up any stains. Relax. Remember that this is not new. Get supplies. Visit the nurse. Talk with another teacher. Bring a period kit. Dress comfortably. Expect a bit of awkwardness. Stay polite and thankful. Stay calm. Tell your teacher you're having your first period. Talk to the school nurse if you're not comfortable talking to your teacher. Call a parent from the front office if you don't feel that you can talk to an adult at school. Ask a friend who has already experienced her period what to do. 