I am a big believer in having my kids keep journals. I believe that the more you practice writing (just like any other skill) the better you get at it. Luke (age 5) has been drawing journals for almost two years, but is really starting to take off with writing in them as you can see below:
Sorry for the bad picture, but it says "He has fire." As you can see, he still writes a lot of capitals (which is a skill we are working on, but he has just started adding periods to the end of his sentences. He noticed as we were reading that sentences had periods at the end of them, and he asked why. Ever since then he has become fascinated with periods!
This page says "He had long nails."
My older boys often use journals to respond to books they are reading as well as to write stories or about their day. They also write math journals as responses to multi-step math problems.
Do your kiddos use journals? If so, in what ways?