Atoms · 4:08
Sketchnote in the works
status paste pack ready — Mr. U draws this one next
Unit 05 · Matter & Chemistry arc · 8th grade
It's all
stuff.
The desk, the air, the beetle, you — all of it is matter, and all of it is built from atoms so small that thirty snips of a scissors gets you there. Welcome to the chemistry semester.
thirty cuts to the atom — try it below
Watch · Khan Academy
The whole story of stuff, in four short films
Cards · Spaced repetition
Say it like a scientist
Flip, type, or match — the deck schedules what you're about to forget, and myth cards keep you honest. (It lives in your browser, no account.)
Sketch · sketchnotes
Draw it to know it
One page per video: print the workbook, fill it in while you watch, then check yourself against the key. Mr. U is drawing these next — the band is ready when they land.
Subatomic · 2:31
Sketchnote in the works
status paste pack ready — Mr. U draws this one next
Elements · 5:13
Sketchnote in the works
status paste pack ready — Mr. U draws this one next
Compounds · 6:01
Sketchnote in the works
status paste pack ready — Mr. U draws this one next
Read · Eleo explains
The beetle's commentary track
One flagship companion for the whole unit — same stuff, beetle's mouth. Audio version lands when it's recorded.
Investigate · Performance expectations
Your prediction vs. the real world
Commit first, then let the data reply. Investigation pages are being designed with Mr. U and land here when they're honest.
Investigations in the works
Models of the atomic composition of matter — the scissors experiment is only the beginning.
in the worksPractice · Math skills
Thirty cuts to the atom
Halve a strip thirty times and the exponent takes you to the atom. Then down the powers-of-ten ladder, density detective work, and counting atoms in formulas. Print it, solve it, check the key.
Myth-busters · tap to flip
Unlearn these three things
Exit ticket · 5 questions
Before you leave the atom
No grade, no stakes — just proof the stuff stuck. Answer all five to earn the stamp.
question 1 of 5
The phenomenon · the scissors experiment
Thirty Cuts to the Atom
Take a 10 cm square of foil. Cut it in half, then in half again, and keep going. Ten cuts: thinner than a hair. Twenty cuts: smaller than a cell. Thirty cuts: about one atom wide. Run the counter and watch the size collapse.
cut 0
10 cm wide
each click halves the square (alternating direction). the counter does the honest math.
Around cut thirty, the piece is about one ten-billionth of a meter wide — one atom. The scissors are useless down there; you can't cut an atom with steel. The Greek Democritus called this hypothetical smallest piece atomos: the uncuttable. He was guessing in 400 BCE. He was right.
Manipulative · the definition
Matter = mass + volume
Matter is anything that has mass and takes up space. Two toolkit measurements from Unit 04: mass rides the balance, volume rides the graduated cylinder. Air qualifies — an inflated balloon literally weighs more. Sort the stuff from the not-stuff.
Pick an item, then file it: matter or not?
Matter
has mass + takes space
Not matter
energy or abstract
0 / 8 filed
The building blocks
Atoms: 118 kinds of Lego
An atom is the smallest piece of an element that's still that element. An element is one type of atom — and the whole universe builds everything with just 118 kinds.
Mostly empty space
If the atom were a stadium, the nucleus would be a marble at midfield and the electrons would be gnats in the nosebleeds. Solid stuff is 99.9999999% nothing.
The three residents
Proton — positive, in the nucleus. Its count decides WHICH element it is. (6 protons? Carbon. Always.)
Neutron — no charge, in the nucleus. The ballast.
Electron — negative, zipping around outside. Chemistry's actual player.
From guess to proof
~400 BCE — Democritus guesses "atomos," the uncuttable.
1803 — Dalton makes it a theory: elements are one kind of atom.
1981 — microscopes finally image single atoms. Guessed it, proved it, photographed it.
Manipulative · powers of ten
The scale ladder
Slide down the ladder — each step is a thousand times smaller. This is Scale, Proportion, and Quantity: the numbers that let one classroom hold both a beetle and an atom.
the beetle
3 cm · 3 × 10⁻² m
our mascot. if he were atom-sized, YOU would be bigger than the solar system.
youbeetlecellvirusatom
Standard: MS-PS1-1 — developing models of the atomic composition of matter (NGSS Lead States, 2013). DCI: PS1.A Structure and Properties of Matter. CCC: Scale, Proportion, and Quantity — one ladder holds the beetle and the atom.