A four year old is way too young to care for a hamster or even an ant farm. I assume (and hope) YOU will care for the pet every day and supervise your children in handling. Keep reading and researching care.
Syrian hamsters will not bite when handled properly. I have had dozens and every one I could kiss on the nose, including Maggie who I rescued biten and screaming in terror from an overcrowded bin; three days later I could kiss her.
Old taming threads must be all over this forum. Do a Search.
LEAVE THE HAMSTER ALONE FOR SEVERAL DAY minimum.
LEAVE THE HAMSTER IN A QUIET PLACE WITH A NICE PLACE TO HIDE AND SLEEP and feel secure.
DO NOT WAKE THE HAMSTER UP.
DO NOT GRAB FROM ABOVE.
DO NOT REACH IN THE HABITAT.
TALK GENTLY TO THE HAMSTER WHILE GIVING FOOD and water.
Let the hamster settle in, and then let the ham walk into a tube and walk out on your hand. Pet gently.
Put back in home.
Eventually the ham will trust you.
Check out this link for a new and very cool trick I added to the others!!