Toby’s Salt Surprise

Toby sees salt beside a cup of water. “Will the grains stay where I can see them?” he asks. Mum brings a second cup and some clean sand. They will compare small amounts without tasting anything.

They look at the dry grains first. Salt and sand may look a little alike, but that does not make them the same material. Mum puts equal amounts of room-temperature water in the two clear cups.

Toby adds a small spoonful of salt to one cup and begins to stir. Soon he cannot see the grains. “Gone!” he says. Mum explains that salt can dissolve in water. It is still there, spread through the water.

In the other cup, the sand does not dissolve. Some grains settle on the bottom after stirring. Toby waits and compares. The two materials have behaved differently in the same kind of water.

The salty water looks clear. That does not prove it is plain water or safe to taste. They know what they added because they kept track. Looking alone cannot tell Toby everything about a liquid.

Mum pours a little salty water into a shallow saucer on a protected shelf. They leave it there for several days. No one heats it or drinks it. Toby checks with Mum when they pass.

Later, the saucer is dry, and salt crystals remain. Mum explains that water can evaporate into the air. The dissolved salt did not vanish. Removing the water has made it easier to see again.

Toby draws the cup, saucer and crystals. “Not seeing something is different from it not being there,” he says. His surprise has become a question he can explain, with the sand cup and salty saucer as clues.