My daughter is 10 months old. She has not started to crawl. What should I do?

I teach my son how to crawl by helping to put his hand in front and push his leg in front and he will know how to push himself in front to get what he ones. I just feel we need to help and motivated them, and they learn very fast from it. I always give him a helping hand, and soon he can do bit by bit on his own. My son is more lazy so need to teach him.