The Role of Bilateral Coordination and Crossing the Midline in Writing

When we think of writing, we often picture a child gripping a pencil and forming letters on a page.

But long before children begin to form words and sentences, their bodies are busy building the foundational skills that make writing possible.

Two of the most important—and often overlooked—are bilateral coordination and crossing the midline.

Understanding and supporting these physical skills can make a huge difference in your child’s ability to write with confidence and ease.

So what are they, and how do they connect to early writing success?

What Is Bilateral Coordination?

Bilateral coordination is the ability to use both sides of the body at the same time, in a coordinated way. This skill is essential not only for daily tasks like dressing, eating, and playing but also for writing.

When a child writes, they need one hand to do the writing while the other hand holds the paper steady.

This is a perfect example of bilateral coordination at work: each hand has a different role, but both must work together.

Children who struggle with bilateral coordination may:

Frequently switch hands during a task
Have difficulty stabilising their paper while writing
Avoid fine motor activities like cutting or threading
Show frustration during tasks that require two hands to work together

Without strong bilateral coordination, writing can feel awkward or physically tiring.

That’s why it’s important to support this skill from an early age.

What Is Crossing the Midline?

The midline is an invisible line that runs vertically down the centre of the body, dividing it into left and right sides.

Crossing the midline means that a child can reach across this line with one hand to the other side of their body—for example, using the right hand to reach over to the left side to grab a toy or write across a page.

Crossing the midline is essential for:

Developing a strong hand preference (hand dominance)
Writing from left to right across a page
Reading smoothly across lines of text
Using the same hand throughout a task instead of switching hands

Children who avoid crossing the midline might:

Switch hands midway through writing or drawing
Only write on one side of the page
Struggle to track text smoothly while reading

If a child hasn’t developed this ability, writing can be disjointed and difficult.

That’s why encouraging cross-body movement is so important.

How These Skills Support Writing

Writing is a complex task that requires:

Physical strength and coordination,
Visual tracking,
And cognitive focus.

Bilateral coordination and midline crossing support writing in several key ways:

🖐️ Paper control – One hand holds the paper still while the other writes
🔤 Fluid writing motion – Moving across the page requires reaching across the midline
🧠 Hand dominance – Consistent hand use builds muscle memory and fine motor control
👀 Visual tracking – Reading and spacing letters relies on tracking left to right

When these skills are in place, writing becomes more natural, efficient, and enjoyable.

Activities to Strengthen Bilateral Coordination and Midline Crossing

You can support your child’s development with fun, movement-based activities that build both gross and fine motor skills.

Here are some ideas to get started:

💪 For Bilateral Coordination:

Playdough rolling: Roll balls or snakes using both hands
Threading beads or pasta: One hand threads, one holds
Cutting shapes: Scissors in one hand, paper stabilised in the other
Drumming or clapping games: Use both hands in rhythm

🤸 For Crossing the Midline:

Big rainbow drawings: Encourage reaching from one side of the page to the other
“Simon Says” with cross-body actions: Touch your left knee with your right hand
Ball games: Roll or toss a ball across the body
Figure 8 tracing: Draw sideways 8s with one hand, large across the page or in the air

Movement builds the brain-body connections that make writing possible.

When to Seek Support

If your child avoids cross-body movements, switches hands frequently, or seems uncoordinated with two-handed tasks, it may be a sign they need extra support.

An occupational therapist can assess and guide you with targeted strategies to build these foundational skills.

Early intervention can help reduce frustration and prevent future learning challenges.