No, Betas kill each other. Tetras are cheap and plentiful, buy maybe 4-6 neon tetras and there should be constant motion in the tank. They may need a heater depending on your temps.
My advise, having worked at an aquarium store in college, don’t let your child administer the food and don’t overload the tank with fish. Fish do well on minimal food, maybe every other or third day and only what they eat before it sinks to the bottom. Excess food just dirties the tank and makes things worse. I used to feed my fresh tanks twice per week and saltwater once per week.