OpenStem

@openstem · Joined Jul 2026

7420 public items8 groups

Note~74 words · 1 min

Sorting and Recycling Materials When you finish with something, it does not have to be gone forever. Many materials can be turned into something new — but only if they end up in the right bin. Which Bin Does It Go In? Before something can b

Chemistry

Chemistry · L1 · Sorting and Recycling Materials

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Note~259 words · 1 min

Colours Change All Around Us Look closely and you'll spot colour changes everywhere — on nails, fruit, toast, and even leaves. A shiny iron nail left outside slowly turns orange-brown. That colour change is called rust. It happens when iron

Chemistry

Chemistry · L1 · Colours That Change

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Note~316 words · 2 min

Air Is Really There Air is all around you, right now. You cannot see it, but it is a real thing, just like water or wood. You can feel air when the wind blows on your face, and you can trap it inside a balloon. Air is not one single thing —

Chemistry

Chemistry · L1 · Air, Breathing, and Gases

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Note~399 words · 2 min

Gas Hiding in a Liquid A fizzy drink — soda, sparkling water, lemonade — has a gas hiding inside it. That gas is carbon dioxide, and it is dissolved right into the liquid, spread through it so evenly you can't see it at all. At the factory,

Chemistry

Chemistry · L1 · Fizzy Drinks and Dissolved Gas

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Note~329 words · 2 min

From Dissolved to Solid Again You already know that salt and sugar seem to disappear when you stir them into water. They dissolve — the tiny pieces spread out through the water so you can't see them anymore. But if you leave that salty or s

Chemistry

Chemistry · L1 · Growing Crystals at Home

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Note~373 words · 2 min

Puffing Up With Bubbles Bread dough and cake batter both start out flat and heavy. But once they come out of the oven, they are light and full of tiny holes. What happened? Tiny bubbles of gas formed inside the dough or batter. As the oven

Chemistry

Chemistry · L1 · Why Bread and Cakes Rise

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Note~310 words · 2 min

How Soap Cleans You already know that sugar and salt dissolve in water, but oil and grease do not. Grease just sits on top of water, no matter how much you stir it. So how do we ever get a greasy pan clean? The answer is soap. Soap Has Two

Chemistry

Chemistry · L1 · How Soap Cleans

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Note~317 words · 2 min

One More Way to Sort Things You already know how to tell a metal from a non-metal. Metals are usually shiny and bend a little instead of snapping. Non-metals are usually dull, and they often snap, stretch, or break instead. There is one mor

Chemistry

Chemistry · L1 · Testing with Magnets

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Note~356 words · 2 min

A Smell Is Made of Tiny Particles When you smell fresh cookies, a flower, or even a skunk, you are not just imagining it. Tiny, invisible particles are coming off that thing and drifting through the air until some of them reach your nose. Y

Chemistry

Chemistry · L1 · Where Do Smells Come From?

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Note~329 words · 2 min

Metal Left Out in the Weather Bike frames, metal fences, garden tools, and playground equipment all spend their lives outside. Rain falls on them, and even when it isn't raining, the air around them often stays damp. Metal kept indoors — li

Chemistry

Chemistry · L1 · Weathering: Why Outdoor Metal Rusts

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Note~386 words · 2 min

Why Salt Melts Icy Roads (and Makes Ice Cream Colder) Salt is just a simple kitchen ingredient. But when you mix it with ice, it does something surprising — it makes it much harder for the water to stay frozen solid. Salt on Icy Sidewalks a

Chemistry

Chemistry · L1 · Why Salt Melts Icy Roads

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Note~303 words · 2 min

Two Secret Inks You can write a message that is completely invisible — until you use a trick to make it appear! Here are two fun ways to do it. Lemon Juice Ink Dip a cotton swab or a toothpick into lemon juice and write your message on pape

Chemistry

Chemistry · L1 · Secret Messages with Invisible Ink

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Note~296 words · 1 min

Why Food Colouring Spreads Through Water Drop a single drop of food colouring into a still glass of water and watch closely. Slowly, it spreads out into curly, cloud-like tendrils. Given enough time, the whole glass becomes evenly tinted —

Chemistry

Chemistry · L1 · Why Food Colouring Spreads Through Water

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Note~455 words · 2 min

Why Helium Balloons Float Up Let go of a helium balloon and it does not just sit there — it rises up, up, and away until you lose sight of it. But a balloon you blow up yourself just sits on the floor, or floats gently at the height you lef

Chemistry

Chemistry · L1 · Why Helium Balloons Float Up

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Note~237 words · 1 min

Sour or Soapy? Acids and Bases in the Kitchen Take a tiny taste of lemon juice, then a tiny taste of a pinch of baking soda mixed in water. They taste completely different, and that difference has a name. Acids Taste Sour Lemon juice, vineg

Chemistry

Chemistry · L1 · Sour or Soapy? Acids and Bases in the Kitchen

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Note~260 words · 1 min

Why a Candle Burns A candle looks so simple — just a stick of wax with a little flame on top. But that tiny flame needs three things at the very same time to keep burning. The Three Things Every Flame Needs How the Wick Feeds the Flame Soli

Chemistry

Chemistry · L1 · Why a Candle Burns

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Note~258 words · 1 min

Density: How Tightly Is Matter Packed? Density tells you how much mass is squeezed into a given amount of space (volume). Two objects can be the same size but have very different densities if one has much more mass packed into it than the o

Chemistry

Chemistry · L2 · Density

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Note~229 words · 1 min

Evaporation and Condensation After it rains, a puddle sits on the sidewalk. A few hours later on a sunny day, it is gone. Where did all that water go? Evaporation: Liquid Water Becomes Invisible Vapor The sun warms the puddle, and slowly th

Chemistry

Chemistry · L1 · Evaporation and Condensation

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Note~241 words · 1 min

Why Salt Melts Sidewalk Ice Faster In winter, you might see people sprinkle salt on icy sidewalks and steps. Why salt, and not just any powder? Salt Changes the Freezing Temperature Plain water freezes at a certain temperature. But when you

Chemistry

Chemistry · L1 · Why Salt Melts Sidewalk Ice Faster

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Note~216 words · 1 min

Milk and Vinegar Curdling Pour a glass of milk and it looks smooth and even. Now add just a small splash of vinegar and stir. Watch closely — something surprising happens. From Smooth to Lumpy Within a minute or two, the milk stops looking

Chemistry

Chemistry · L1 · Milk and Vinegar Curdling

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Note~266 words · 1 min

Mixtures vs. Solutions When you stir two or more things together without making anything new, you have made a mixture. But not all mixtures look the same. Cookie Dough: A Mixture You Can See Picture chocolate chip cookie dough. You mixed th

Chemistry

Chemistry · L1 · Mixtures vs. Solutions

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Note~266 words · 1 min

Oil and Water Don't Mix Look at a bottle of salad dressing sitting on a shelf. You will almost always see it split into two layers — one part on top, one part on the bottom. Two Layers, Every Time The top layer is oil, and the bottom layer

Chemistry

Chemistry · L1 · Oil and Water Don't Mix

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Note~258 words · 1 min

Hidden Colors in a Black Marker A black marker looks like it draws just one plain color: black. But many black markers are secretly a mix of several colors blended together so well that they look black. How to Reveal the Hidden Colors As th

Chemistry

Chemistry · L1 · Hidden Colors in a Black Marker

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Note~236 words · 1 min

Solid, Liquid, or Gas? Look around your kitchen. A spoon, a puddle of juice, and the steam over a hot pot are all matter — but they behave in three very different ways. Three States You Already Know Same Stuff, Different Form Here is the su

Chemistry

Chemistry · L1 · Solid, Liquid, or Gas?

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Note~126 words · 1 min

Acids, Bases, and Indicators Substances can be sorted into acids, bases, or neutral. An acid has a sharp or sour taste — think lemon juice or vinegar. A base (also called an alkali when dissolved in water) feels slippery — think soap or bak

Chemistry

Chemistry · L2 · Acids and Bases

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Note~289 words · 1 min

Groups and Periods The periodic table lines up every known element by atomic number — the number of protons in each atom. Element number 1 (hydrogen) comes first, element number 2 (helium) comes next, and so on, all the way past 100. The ta

Chemistry

Chemistry · L2 · Periodic Table Basics

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Note~306 words · 2 min

The pH Scale Litmus paper can only tell you whether something is an acid or a base. But chemists often want to know just how acidic or how basic something is — and that's what the pH scale is for. The pH scale runs from 0 to 14. A pH of 0

Chemistry

Chemistry · L2 · The pH Scale

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Note~285 words · 1 min

Reactants Become Products A chemical reaction turns one set of substances into another. The substances you start with are called reactants. The new substances the reaction makes are called products. Chemists write this down as a word equati

Chemistry

Chemistry · L2 · Chemical Reactions & Word Equations

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Note~409 words · 2 min

Separating Mixtures In a mixture, the substances are just mixed together — not chemically joined — so each one keeps its own properties. That means we can use those different properties to separate the mixture back into its parts. Which met

Chemistry

Chemistry · L2 · Separating Mixtures

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Note~416 words · 2 min

Metals and Reactivity Not all metals behave the same way. Some, like potassium and sodium, react so fast and so strongly that they must be stored under oil for safety. Others, like gold and platinum, barely react with anything at all — whic

Chemistry

Chemistry · L2 · Metals and Reactivity

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