First graders with poor “number sense” rarely catch up in math skills, concludes a University of Missouri study. But it’s not clear how parents or preschools can teach number sense.

What’s involved? Understanding that numbers represent different quantities — that three dots is the same as the numeral “3″ or the word “three.” Grasping magnitude — that 23 is bigger than 17. Getting the concept that numbers can be broken into parts — that 5 is the same as 2 and 3, or 4 and 1. Showing on a number line that the difference between 10 and 12 is the same as the difference between 20 and 22.

Factors such as IQ and attention span didn’t explain why some first-graders did better than others.

Math learning disabilities often aren’t diagnosed till fifth grade, much too late, says Dr. Kathy Mann Koepke, of NIH’s National Institute of Child Health and Human Development.

David Geary, who conducted the Missouri study, thinks parents can help children develop number sense before they start school.  NIH’s Mann Koepke urges parents to talk to young children about “magnitude, numbers, distance, shapes as soon as they’re born.”

– Don’t teach your toddler to count solely by reciting numbers. Attach numbers to a noun — “Here are five crayons: One crayon, two crayons…” or say “I need to buy two yogurts” as you pick them from the store shelf — so they’ll absorb the quantity concept.

– Talk about distance: How many steps to your ball? The swing is farther away; it takes more steps.

– Describe shapes: The ellipse is round like a circle but flatter.

– As they grow, show children how math is part of daily life, as you make change, or measure ingredients, or decide how soon to leave for a destination 10 miles away,

However, researchers don’t really know why some kids get that 3, three and xxx are the same thing and others don’t. Children with poor phonemic awareness need to work harder to distinguish the sounds in a word. Perhaps some kids need to work harder — or differently — to see mathematical relationships.