Why use a stroke based approach to teach letters in kindergarten? 

The drawing of pictures and writing of letters and numbers uses a series of curved and straight lines in different directions that are linked to form patterns, shapes, letters and numbers. 

Here are the most common strokes used to form lower case letters.

A stroke based approach to learning to print letters is a matter of building a library of motor plans for the different combinations of strokes that are used to produce letters and numbers, so that a letter, or series of letters can be pre-planned and written without the need for visual guidance. An important aspect of this learning is the increasingly strong association between the sound of the letter (phoneme), the shape of the letter (grapheme) and the motor plan for the letter.  

Learning the motor plan for the letter occurs when the child practices writing letters by linking the strokes for the letter, using smoothly executed movements which are not constrained by accuracy demands such as needed for writing neatly between the lines.

 ​Once the motor plan is well established and the child is able to link the strokes to form letters  in a smooth manner without the need for visual guidance, attention can be given to writing accurately between lines. 

Learning the motor plans for the letters occurs when learners are first given the opportunity to practice forming letters using smoothly executed movements which are not constrained by accuracy demands. Once the motor plan is well established and the child is able to link the strokes to form letters in a smooth manner without the need for visual guidance, attention can be given to writing accurately between lines.

Many approaches to teaching handwriting emphasize tracing letters as a way to learning the shape of the letters. However tracing letters shifts the child's strategy for writing letters away from a fluent pre-planned action that link the letter strokes to using to using small visually guided movements needed to keep the marker between the lines of the letter being traced.  This reliance on visual guidance inhibits learning the motor plan for the letter. 

How children acquire the ability to produce accurate pre-planned strokes  

At the beginning of the kindergarten year young children with good motor coordination and attention abilities will have acquired the ability to draw straight and curved lines (called strokes) to form a variety of shapes and patterns.  

Over the course of the kindergarten (Gr R) year, children who are given the opportunity to do a lot of drawing will  improve their ability to draw lines (strokes) that are smooth,  and to link these strokes together to form shapes and patters that are well spaced and sized.

Learning to print  letters and numbers is an easy task for children who have acquired the coordination and graphomotor abilities to produce and link the strokes that make up the letters.  All they need to do is learn the motor plan for each letter and very quickly are able to make the brain connections that link the sound of the letter (phoneme), the visual image of the letter (grapheme) and the motor plan that produces the letter. 

Why a stroke based approach with guided practice is important in DCD and ASD

Children with DCD and autism have difficulties learning new motor plans (sometimes referred to as internal models) because of differences in the way the brain is wired.  Most approaches to teaching handwriting rely on tracing over printed letters which encourages the child to use continual visual monitoring of their movements. This practice inhibits the formation of motor plans as the child does not have to recall the motor plan to write the letter, instead the letter is formed by a series of short strokes guided by visual feedback.

Children with autism have particular difficulties using online visual feedback, but make good use of proprioceptive feedback from the muscles and joints. A stroke based approach which emphasizes the development of motor plans for letter formation, builds on the child's sensory strengths and implicit learning abilities. Once the letter is completed children with autism are able to evaluate the shape and size ot the letter and use their superior ability for seeing detail to provide feedback that can be used to adapt the motor plan.

A stroke based approach, along with guided practice provides children with DCD and autism the best environment for learning and improving their handwriting.