What are the signs of puberty?

I didn't understand what periods were until I experienced them firsthand. The day before I got my period, I noticed some blood and assumed I had an infection. I confided in my older sister, who advised me to let her know if I experienced it again next month. The following day, my focus was compromised during classes and sports. I asked my teacher for permission to use the restroom and was taken aback when I discovered blood on my pants (luckily, they were dark-colored). When I explained the situation to my teacher, she provided me with a pad, and it was then that I realized I had reached puberty.