With well established pencil grip, your child now shows expertise in writing letters, both upper and lower case. He has the sense of keeping the writing in the space on the page and will be able to write letters within the lines as he is better with baseline orientation.
He will also take into account the other aspects of handwriting skills like spacing, sizing and alignment of letters while writing. The more he reads, he will understand where one word ends and another begins. Simultaneously, he learns the right spacing between two words.
What you can do
You can try many activities which will work on improving your child’s baseline orientation. i.e ‘writing within the lines.’ For instance, take a sheet of paper where you draw a design of basic straight and curved lines. Ask him to use Wiki Stix and have him press it on the lines, following the path.
Another activity can be to squeeze glue over lines such as shapes, letters, tracks, etc. He will apply the same logic while writing to keep letters within the lines.