No, it's not. Middle school is a time for learning, making friends, and developing oneself in a non - sexual way. Having sex at this stage can cause a great deal of emotional distress as well. Teenagers may not be able to handle the complex emotions that come with sexual relationships. Moreover, it can disrupt their educational progress and future prospects.
It is completely inappropriate. Middle school students are still minors, physically and mentally not ready for sexual activities. It can have serious negative impacts on their health, including the risk of sexually transmitted diseases and unwanted pregnancies. Also, it goes against the norms and values of society which expects minors to focus on their studies and personal growth.