Bad idea. Buying random stocks after “researching” in the hope that they’ll go up is gambling with extra steps. They’ll learn a lot more with a real money account. Fidelity lets you open a teen brokerage account + debit card at age 13:
https://www.fidelity.com/go/youth-account/overview
Teach them the right way to invest by simply plowing their extra birthday/holiday cash into VTI/VOO/etc. as often as possible. Then go back and review their performance 1, 3, 5+ years down the road, as well as stressing how their savings rate had the biggest impact when starting out but then growth via gains & dividends starts to snowball at a certain point. The real lesson is having patience and consistency. Profitable investing is slow and boring.
“The stock market is a device for transferring money from the impatient to the patient.” -Warren Buffett