My daughter is in kindergarten and we are so lucky to have a really wonderful teacher. Early on in the year the teacher spoke with us about her plans to teach them how to write sentences and short essays. I was pleased with her aggressive approach. One of her requests to us what that when she writes that we do not spell any words for her. We were supposed to encourage her to write the words how they sound. Spelling them for her does not get her to think about the word and phonics. So we did what sounded reasonable to us.
I deeply feel from that logic that my daughter has really learned so much about phonics and words and has improved in her spelling all on her own. And the essays we get from her are so cute and funny. The words are sometimes really big and to see her give her 100% effort on getting them right really warms my heart...and helps her to learn so much more. So if you want to really help your kids learn words and how to spell them, let them make mistakes on their own.