How can I get financial aid for children karate classes?

Answer 1

ask the instructor.
most classes are very cheap and you will see the many instructors dont make so much money and barely make ends meet as it is. Its definately a labor of love. You should get to know your sensei, sifu, etc and choose for your children by quality of human instructor rather than any other factor as a priority.
If they cant make time to meet with you, go to another dojo, gym, etc right away because thats a red flag.