Here are some ways you can acquire followers for your account:
Once you convert your Instagram account to a Professional account, you will have access to statistics about your account, called Insights. You can access these by going to your profile and clicking the Insights button. This will show you information about the people who are viewing and engaging with your posts. One metric to look for here is that your audience age matches the age of your students. This will be solid evidence that you are reaching your target demographic.