# The Mystery of the Three Containers

This brain teaser uses the particle model of matter, which explains how tiny particles behave in solids, liquids, and gases ([Guiding question](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/36472), [Understanding](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/36476)). You will use clues about particle spacing, movement, and attractive forces to figure out which container holds which state of matter ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/36475), [Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/36477)).

![Figure 1: Three clear containers of the same size sitting on a wooden classroom table, each showing a different swirling pattern of tiny dots inside](https://goa-cc-uat-aili-app-001.azurewebsites.net/api/generate/3a75d302-25be-49b9-9ff1-b23da1e3d6f8/asset/740)

## The puzzle

A scientist labels three sealed containers A, B, and C. Each one holds matter in a different state: solid, liquid, or gas. She writes down three clues about the particles inside, but she mixes up the container letters. Use her clues to match each container to its correct state.

Clue 1: In container A, the particles are packed close together and only vibrate in place. They do not slide or spread out.

Clue 2: In container B, the particles have the weakest attractive forces of the three containers, and they move constantly in all directions, spreading out to fill the whole space.

Clue 3: In container C, the particles are close enough to slide past each other, but they are not locked into a fixed pattern the way container A's particles are.

Which container is the solid? Which is the liquid? Which is the gas?

## Hints

Hint 1: Think about which state has particles that barely move from their spot. That matches only one of the three clues.

Hint 2: Attractive forces are strongest in solids and weakest in gases ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/36475)). Use that fact to sort container B right away.

Hint 3: Once you know the solid and the gas, the container that is left over, the one where particles slide past each other, must be the third state.

## Answer key

Container A is the solid. Its particles are close together and vibrate in place without sliding, which matches the description of a solid ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/36475), [Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/36475)).

Container B is the gas. Its particles have the weakest attractive forces and move constantly in all directions, spreading to fill the whole container, which matches the description of a gas ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/36475)).

Container C is the liquid. Its particles are close enough to slide past each other but are not fixed in place like a solid's, which matches the description of a liquid ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/36475), [Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/36477)).

The reasoning uses the particle model idea that attractive forces are strongest in solids and weakest in gases, with liquids falling in between ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/36475), [Understanding](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/36480)). Sorting by attractive force strength first, then by whether particles vibrate in place or slide past each other, solves the puzzle in three steps.

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*AILI game · language en · model claude-sonnet-5 · generated 2026-09-17 · id 3a75d302-25be-49b9-9ff1-b23da1e3d6f8*

### Sources

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- node:n4: Sciences › Science (K–6) › Grade 5 › Matter: Understandings of the physical world are deepened by investigating matter and energy. › How can states of matter and other physical properties be explained by using the particle model of matter? › Students investigate the particle model of matter in relation to the physical properties of solids, liquids, and gases. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/36477)
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