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Don't only interact with the "popular" kids, but with everyone, including the shy kids. Contribute well in group or partner projects. Don't fake your kindness for popularity, take a genuine interest in others. Do things for others, not just yourself. By doing this you will strengthen your friendship. You could also ask if they would like to meet with you somewhere else, such as a cafe, shop or park, this is an ideal option if whoever you live with doesn't like visitors. They'll get a chance to see pictures of you and your old friends. It also gives you a chance to communicate with them outside of school.  You've made it.

Summary:
Continue to be social. Invite someone over to your house as soon after you have their phone number. Ask people for their phone number, e-mail address or name on social media. Friend request people on social media you met during the day, look at their profiles and learn who is friends with who. Congratulate yourself.