Foldscopes -Biology
You're about to build a real microscope out of paper, then use it to see things your eyes can't. Start with a plant cell, move to a living animal cell, and end by finding the exact place inside your own body where your DNA is stored. First stop: your own microscope.
A Foldscope is a microscope you fold out of one flat sheet. It weighs less than a AA battery and magnifies up to 140× — enough to see a single cell. A scientist named Manu Prakash invented it so every student on Earth could own a microscope. Today, yours.
Watch the video once, all the way through. Then punch out the parts and fold your Foldscope by following the same steps. Crease every fold hard with your fingernail. This video also shows you how to load your first sample.
Now find something from the room to look at. This video views an ant — try that, or a piece of leaf, a thread, or a strand of your hair. Slide it in, hold the Foldscope right up to your eye, aim at a window or light, and move it slowly until the image snaps into focus.
Clip the magnetic coupler over your phone camera, line it up with the lens, and photograph what you found. Post it to The Wall at the bottom of this page — put your first name in the Subject line.
That tiny glass bead is a lens. It bends light so the rays spread apart before they reach your eye, and your brain reads that spread as "bigger." Same physics as a lab microscope, folded into paper.
Point your Foldscope at something alive. Onion skin is one cell thick, so you'll see the actual bricks that build a living thing — and then you'll watch those bricks react in real time.
Iodine stains skin, clothes, and desks brown, and it does not wash out. Gloves on. One drop means one drop.
Watch the video, then do it. Peel the thin, see-through skin from inside an onion layer, lay it flat on a slide with no wrinkles, add one drop of iodine, and lower a cover slip on top. Focus your Foldscope. You're hunting for a brick-wall grid — box-shaped cells in rows, each with one dark dot: the nucleus. Hold that word.
Take a fresh piece of onion skin and soak it in salt water for 10–15 minutes, then view it. Watch the cell insides shrink and pull away from the walls. That's plasmolysis — the salt is pulling water out of the cells. The video shows what to look for.
Don't just wait. In your field notebook, draw one onion cell before the salt and label the nucleus and the wall. Then post your best focused shot to The Wall — first name in the Subject line.
Water always moves toward where there's more salt. Outside the cell is now saltier than inside, so water leaves and the cell deflates like a slow balloon. Same reason salt preserves food, and the same reason you get thirsty after chips.
You've seen a plant. Now look at yourself. The cells lining the inside of your cheek come off easily and carry the one thing this whole day is building toward.
Your own toothpick only — never share one. Methylene blue stains like iodine does: gloves on, one drop. Used toothpicks go straight in the trash.
Gently scrape the inside of your cheek with a clean toothpick — no need to press hard. Stir the toothpick into a drop of methylene blue in the center of a clean slide, then lower a cover slip on top. The stain makes the inside of the cell pop. Follow the video, then use your own Foldscope.
Focus and find: the cell membrane (the soft outer edge), the cytoplasm (the filling inside), and the nucleus (the dark blob in the middle). That dark blob is the headquarters of the cell.
Put your onion drawing next to your cheek cells. Onion cells are stiff rectangles with a thick cell wall. Your cheek cells are soft, rounded blobs with only a flexible membrane. Turn to your group: why would a plant need rigid walls when you don't? Come up with a reason together.
That dark nucleus in the middle of your cheek cell? It's where your DNA is coiled up — all of it, the full set of instructions for building you. You are looking straight at the container that holds your genetic code. In Part 2, you're going to pull that DNA out of the container until you can see it with your bare eyes.
Post your cheek cells to The Wall — first name in the Subject line. Try to catch the nucleus in focus.
Scan this to upload your photos. Every foldscope find, onion cell, and cheek cell goes here.
Put your first name in the Subject line so we know whose discovery it is.
You built a microscope, saw a plant cell change before your eyes, and found the vault where your own DNA lives. Next: Part 2 — pull that DNA out and hold it.