Setting: After classes have ended, Aviv, Jalen, and Xo are in front of their school, trying to decide what to do this afternoon.
Aviv: Hey, do you want to go visit the world’s tiniest solar-powered food factory?
Jalen: Now? Where?
Aviv: Sure…. it’s right behind the library.
Xo: What? In the school garden? Since when is there a factory there?
Aviv: Let’s go check it out. Farmer Raquel may still be there.
Narrator: The friends walk to the garden. The gardening teacher, Farmer Raquel, is nearby, collecting fallen leaves for the compost pile.
Xo: OK, I give up. Where is your tiny solar-powered food factory?
Aviv: Right here, and here, and here. All around us. Millions—maybe billions—of them!
Jalen: Yeah, right. Are you in some alternate reality, dude? I don't see anything.
Aviv: Just because you can't see them, doesn't mean that they're not there. They're so small, they're microscopic. What we need is a microscope and a… uh… specimen.
Jalen: Why do we need a spaceman?
Xo: (laughing) Sheesh, Jalen. Aviv said SPEHS-uh-mun. Specimen. A sample. But of what?
Aviv: (picking up a small onion from the basket held by Raquel, who came over to see what was happening) How about this? We can use a thin layer of onion, just the skin.
Xo: Oh, I get it! You're talking about plants! I never thought of plants like that, but you're right—plants really are solar energy plants, solar energy factories.
Jalen: This is confusing! Plants are…energy plants? Huh?
Aviv: Well, actually, I don’t mean the whole plant. The real factories are the millions of cells that make up each plant. Each cell is like a tiny machine that uses sunlight to change air and water into fuel.
Jalen: Fuel? Do you mean biodiesel?
Aviv: Kind of, sort of. Fuel like food. Plants have been doing this as long as they've been around. Is that about right Farmer Raquel?
Raquel: Absolutely! Plants make their own food. They convert the sun’s energy into sugars—something that they can store and access later as an energy source. Plant cells power themselves, using energy from the sun—solar power. So a plant cell really is a tiny solar-powered food factory. Humans have never invented any kind of nanomachine as cool as the cell, the basic unit of all life. Here, let’s take that onion into the shed to take a closer look.
Farmer Raquel helps the three friends mount a thin piece of onion skin onto a slide and then look at it through the microscope.
Raquel: Look closely. What do you see?
Xo: It looks like a strange brick wall.
Raquel: Each “brick” is a cell. They look flat, but just like bricks they are totally 3-D. And you're right that there are walls in there. Those thick lines around each plant cell are cell walls. Just inside each walled-off space, there are membranes for each cell, too thin to see.
Jalen: The cells have some kind of brains?
Raquel: Oh, no, not brains but membranes. A very thin boundary between the inside and outside of any cell. It's like a wall, but thinner and more wiggly.
Aviv: Oooh! I see dark dots. Looks like there's one on each cell.
Raquel: Those are the nuclei. Each dot is the nucleus of one onion skin cell. It's the closest thing the cell has to a brain. The nucleus is the control center, and it has the cell's DNA.