Crayola has alphabet coloring pages to practice both print and cursive writing. My son uses these coloring pages. He is 5. We haven't started cursive writing yet, but his print is very clean after using these coloring pages.
Each coloring page has one line for practicing lower case and one line for upper case, along with a box to draw a picture of something that starts with that letter. I usually print out the writing practice page and the simple alphabet letter coloring page at the same time. My son loves to color and draw. The drawing and coloring help motivate him to do the writing as well.
The coloring pages on crayola are free. When I started having my son practice writing, we did one letter a day. Now we are doing two letters a day for three days a week (Monday, Wednesday, Friday). On Tuesdays and Thursdays, we use the Starfall (the free stuff) letter practicing pages to practice writing. He has finished most of the prints, so I am using the blank writing sheet on Starfall to have him write a two or three sentence little story. He draws a picture of the story on the other side of the paper. I think the crayola site has better cursive practice pages than Starfall's cursive pages. However, Starfall is great for teaching reading and practicing print.
You could try the crayola and starfall sites for your 6 year old. I would probably have your 11 year old keep a daily journal. If he doesn't know what to write about, you could give him a topic each time. Topics don't have to be his private thoughts, if he is reluctant to share that with you. He can write about "Why spaghetti is his favorite food" for example. Nothing threatening to his privacy, yet he can still be creative if he wants. I would have him at least write one paragraph a day. Of course it must be neatly written, or he would have to do it again.