We talk about words as if they're something a child knows? Do they know what a FLAMINGO is? Do they know all their colors? Do they know how to spell COUSIN? Or how say SERENDIPITY? Do they know the past tense of GO?

These are important things to learn. And kids have to learn all this stuff for thousands of words.

But is that the whole story?

It's not enough to just know a word... children need to be able to access all that knowledge fast. 

Do the math:

Your typical 1st grader probably knows a 4000 words.

Speech rolls in at a rate of maybe 5 words / secs.

That means that children have to sort through 4000 words every 200 milliseconds!

That's hard.

Moreover, once they find the right word, they've got to sort out its meaning and integrate it into the sentence (and maybe come up with something to say themselves).

Words are not just knowledge -- they're a skill.  Think about the skills you know -- driving, riding a bike, cooking, playing an instrument, working your televisoin or your phone.  Do you have to think about these ?  Could you even describe how to do these things to other people? These are things that are fast, automatic and unconscious.   And yet they're flexible and useful.

So are words!  Children need to approach language and reading like skills.  And scientists do to.  That's the goal of Growing Words.  And that's why we use new technologies like eye-tracking to measure them.