You can go to school if you feel a little nauseated. Try to make your nausea better by chewing on pieces of ginger and sipping on some sparkling water which helps to decrease acidity in your stomach and lessen nausea. Stay away from fatty, processed, and sugary foods. See how you feel during the day. If you start to feel worse after you get to school or experience other symptoms such as vomiting or diarrhea you may want to go home to rest, rehydrate, and relax until you feel better. Knowing the cause of your nausea will make you help with the decision of whether or not you can go to school.