What do you do if you lost your phone in school?

i lost mine on the school field and looked and looked for it and i couldnt find it, it was a samsang galaxy and i wanted to cry, it was $450. never found it, i lost it for like 5 min and it was gone, people have no hearts ha, always buy a cheap phone so when you lose it it you wont care as much as you would care for a $4000000000 dollar phone, i have a useless one now, ha bad life lesson but well learnt (: