If it's important to you that they would know, then you should tell them. However, before you do so keep a few things in mind and think about it thoroughly first. You're still young and at your age you're still discovering certain things. I'm not going to say you wouldn't be bisexual, because you are what you feel you are. If you feel like you are bisexual, then you are. I'm not saying you're too young to know your sexuality, but I'm curious what makes you think that you're bisexual. At your age it is normal to be curious and to wonder about both genders. This does not automatically indicate that you would in fact be bisexual. I think there's a possibility that you're bi-curious. As a teenager it is totally normal to go through that stage. For some this curiosity is more like a one time thing, while for others they find out that they are indeed not straight. If you'd like to talk more about this, you can always message me and I can try to help you to figure this out.