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Where Did the Sugar Go? · When a substance dissolves, its particles spread out and mix among the water particles but are still there · NGSS 5-PS1-3

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Where Did the Sugar Go?

with Atlas

Atlas the friendly guide stands at a bright kitchen counter, stirring a clear glass of water with a spoon, watching tiny sugar specks slowly disappear into the swirling water while sunlight shines through the glass.

Explain that dissolving means tiny particles spread out and mix among water particles.
Predict that a dissolved substance is still present even when it cannot be seen.
Identify taste, weight, and evaporation as clues that hidden particles are still there.

Key terms

Dissolve: When a solid spreads out into a liquid.
Particle: A tiny piece of matter too small to see.
Evaporate: When liquid water turns into invisible gas.
Clue: A hint that helps you figure something out.

Where the Sugar Goes

When sugar dissolves, it does not disappear at all. Sugar is made of tiny sugar particles. When you stir sugar into water, those particles break apart from each other and spread out among the water particles. They move and mix all around, like tiny dancers spreading across a dance floor. The particles are still in the glass, just too small and too spread out for your eyes to see. Nothing is gone, it is only hidden.

Clues It Is Still There

How do we know the sugar did not vanish? We look for clues. The water tastes sweet, so the sugar must still be there. If we weigh the glass right after stirring, it weighs the same as before, so no mass left. If we let all the water evaporate into the air, the sugar is left behind and we can see it again. All three clues together show the hidden sugar particles never disappeared.

Worked examples

Show sugar is hidden, not gone.

Stir a spoon of sugar into the water until it disappears from sight.
Taste a little safe sugar water, and notice it is sweet.
Let the water dry away and see the sugar left behind.

Answer: The sweet taste and leftover sugar prove the sugar was hidden, not gone.

Hi, I'm Atlas! Let's solve a kitchen mystery together. I stir a spoonful of sugar into a glass of water. Round and round it goes, and POOF, the sugar seems to vanish! But did it really disappear? No, it did not. Here is the secret: everything is made of teeny-tiny pieces called particles, far too small for our eyes to see. Water is made of water particles. Sugar is made of sugar particles. When sugar dissolves, its particles break apart from each other and spread out. They move among the water particles and mix in all around them — like tiny dancers spreading across a dance floor. They are still in the glass, just spread out and hidden! How do we know the sugar did not vanish? We have clues. First, the water tastes sweet, so the sugar is still there. Second, if we weigh the glass right after stirring, it weighs exactly the same as before we added the sugar — that mass did not go anywhere! Third, if we let all the water evaporate, the sugar gets left behind and you can see it again. Safety first, scientists: we only taste things when a trusted grown-up says it is safe, like sugar or salt in a kitchen. We never taste mystery liquids. If you ever feel stuck, just look back at our clues: taste, weight, and what happens when water dries away. They all prove the hidden particles are still there!

Activity

Sort each card into Dissolves in water or Does not dissolve in water.

Practice

Where do the sugar particles go when sugar dissolves in water?

Name one clue that shows dissolved sugar is still in the glass.

Common mistakes to avoid

Dissolved sugar is gone forever.The sugar particles are still in the water, only spread out and hidden.
Sugar turns into water when it dissolves.Sugar stays sugar; its particles just mix among the water particles.

Check your understanding

You stir sugar into water and it disappears from sight. What really happened to the sugar?

A common idea is that dissolved sugar is gone forever. Why is that idea wrong?

Which clue best shows that dissolved sugar is still inside the glass of water?

Atlas lets the water in the sugary glass evaporate completely. What would she find left in the glass?

Recap

When sugar dissolves, its tiny particles spread out among the water particles and hide from our eyes. The sweet taste, the same weight, and the leftover sugar after evaporating all prove the sugar is still there.

Reflect

What other things have you seen dissolve in water?