Letting The "Teachable Moment" Pass

"Don't worry Leon, you can always make some more blood."

I heard Luke say it in passing, consoling his friend, as I was on my way to somewhere else. Not having heard what came before or after, it struck me as both hilarious and intriguing. I couldn't help but try to bring it up again. When next Luke and I met on the playground, I said, "You can always make some more blood."

"It's true, Teacher Tom! Your heart pumps and makes more blood. That's why you don't run out when you bleed." Luke knows a little something about bleeding. "And you know what else? Blood is really blue."

I was sitting on the ground with Audrey and a couple of other kids. Audrey interrupted, "No, blood is red."

"No, really," Luke said, turning to her persuasively, "It's blue inside, but when it comes out it looks red."

"Luke, it's red. I've seen it."

"No really, it's true, it's blue."

I thought I could clarify. "I think what Luke is saying is that blood looks blue when it's inside our body. See my vein?" I showed her my inner wrist. "Doesn't it look blue? Veins are how blood flows in our bodies."

Luke supported me, "That's right, Teacher Tom. That's what I'm saying."

But Audrey had other information. "No, that means the blood is flowing to your heart, and it's red when it flows away from your heart. That's the way blood flows: around and around." She drew a circle in the air with her finger.

Some of the other kids were fascinated with studying the visible veins in their wrists and I was distracted into that conversation, but the science debate continued between our two experts. By the time I re-focused on them Luke was saying, "I guess we're both right."

And Audrey replied, "Yeah, we're both right."

Friendship won out over being right, but not over science. Luke was, of course, correct in his assertion that blood inside the body -- as seen through the skin which reflects blue, but absorbs colors of other wavelengths -- appears blue to the human eye. And, of course, that is the nature of color: we only see what is reflected. It's why everything appears to be the same color, black, in the pitch dark. Audrey was correct in her assertion that blood flowing away from the heart tends to be a brighter red because it is highly oxygenated, while on it's return trip it tends to be a sort of purplish-red because it is oxygen-depleted. 

It's tempting, as an adult with a little more information, to step in and correct the flaws in their arguments, to give them the correct, or more correct, or more complete answer. This is the sort of conversation that we so often jump on as a "teachable moment," but I chose to let them conclude like this. Science is built on inquiry and collegial debate, just like this one. (The angry debate is for politicians and theologians who are too often more invested in winning arguments than understanding)

Luke and Audrey came to the table with essentially true, but incomplete information, which is how we all go through life every day. They each walked away with a little more truth, but their knowledge, like that of all scientists, remains incomplete. That is what drives the scientist, not the knowledge, but the incompleteness, the wanting to know. Science is about discovery and when we leap in with all our grown-up "knowledge" we too often rob children of what makes science, or anything for that matter, worth pursuing.

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