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Motor Milestones

What is crossing midline?

Dr. Allison Mell, DPT
October 25, 2022
What is crossing midline?

Have you heard of the term “Crossing Midline”?

It kind of sounds like a gymnastics skill doesn’t it? Maybe it is one, I have no idea, but in the world of child development, this term refers to the ability to cross the imaginary line running down the center of your body dividing the right and left sides. The two halves need to work together to “cross over” this imaginary line to do basically everything from scanning a bird flying overhead, swinging a bat during a little league game, buckling a seatbelt, brushing teeth, and writing across a paper.

You may be asking yourself why this information is important for you to know about. Well, as the eyes, arms, and legs cross the imaginary midline, the right and left sides of the brain are busy chatting with each other. This communication and activity connecting both sides are also creating more and more connections that result in being able to accomplish higher level tasks. If crossing midline (or this communication) is not happening, hand dominance may not be established, which can negatively affect both fine motor and gross motor skills. It can also greatly impact school based activities like copying notes from a board, reading efficiently, and participating in team sports.

Crossing midline develops over time-  we are actually not born with this skill. It begins around 3-4 months when babies start visually scanning without moving their heads. They may start looking at toys overhead or spot their bottles off to the side and move their eyes to watch rather than moving the whole head to see. The crossing midline skill fully integrates by 8-9 years old when children can now accomplish any task that requires their eyes, arms or legs to cross the center of their bodies. Check out my membership for lots of activities that develop crossing midline through play.

Over the course of your child’s first decade (I know, that sounds like forever in the world of raising children), you will notice those crossing midline skills if you’re on the lookout.

Here are some examples of what you’ll be seeing along the way:

  • Babies visually track across the midline without moving their heads at around 3-4 months
  • Babies reach across midline for food and toys at approximately 6 months (before then, baby will reach for something on his right side with his right hand and for something on the left side with his left hand)
  • Babies transition from sitting to crawling by crossing midline between 7-10 months
  • Toddlers can draw a horizontal line across a paper at around 2.5 years old
  • Children can easily cross midline for more advanced tasks like brushing teeth and sports around 4 years old (hello little league!)
  • Between 8 and 9 years old, children’s movements and skills are more fluid and coordinated as crossing midline fully matures.  

Are there any concerns I would notice if my child is struggling with crossing midline?

  • If your toddler or preschooler consistently swaps hands while coloring, using the left hand to color on the left side of the paper and the right hand to color on the right side of the paper.
  • If your preschooler passes an object from one hand to the other instead of crossing over the midline, for example, transferring a block from the right hand to the left to place it on a tower
  • If your child has difficulty visually scanning while reading or playing sports
  • If your child struggles with word searches, mazes, or connect-the-dot activities

Whether you notice difficulty with this skill or not, activities that involve crossing midline help develop the brain.

Here is a list of games that will challenge your child to cross over the center of the body without even knowing it!

  • Twister– Your child will be busy weaving arms and legs over each other to land on the colorful spots.
  • Simon Says- Use instructions like “put your right hand on your left elbow” to incorporate crossing midline right into the game.
  • Pop bubbles– Instruct your child to only use her right or left hand to do the popping. The eyes and hand will both work across the center of the body to pop all the bubbles. This is also a great activities for babies to visually track all the bubbles before they know how to “pop”
  • Hot potato game- Sit in a circle with friends or family and pass a ball or bean bag around and around until the song stops. As your child takes the ball from one person and passes it along to the next person, he’ll be crossing his midline.
  • Spot It – this is a game of visual perception, matching one item on your card to an item on the center card. It’s a great for visually scanning, forcing the eyes to cross back and forth over the midline.
  • Cleaning Games- Kids LOVE this! Try washing the car or windows with only one hand. Kids love to help out so give them a rag and get going! Encourage them to start with one hand, then switch to the other!.
  • Toe touches across the body- Bending diagonally, have your child touch his right hand to his left toes and his left hands to his right toes. Fun fact, this is a great exercise for you too, so get down on the floor and join them!

Bottom Line:

Crossing midline is a skill that helps us cross over the imaginary line running down our bodies separating the right and left sides. Crossing midline is developed over time (almost a decade!) as the brain matures and builds more communication between the right and left halves. Babies begin crossing midline using their eyes to track across their visual fields without moving their heads, toddlers start eating foods using their fingers or utensils with only one hand instead of both, and children develop hand dominance and become more coordinated to play sports and read using their crossing midline powers. The more crossing midline activities young children engage in, the easier it is for the brain to form these necessary connections between both sides. Help you child with this skill by blowing bubbles over head and popping with just one hand, wash the car or windows with only one hand, play games like twister and hot-potato, and hand you things without passing them from one hand to the other first.


Dr. Allison Mell is the founder of Tots on Target and a physical therapist based out of New Jersey.

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