Where the sugar goes

What happens to sugar when it dissolves in water? Activity 7.2 finds out. Do it with a teacher or adult, and never eat or drink anything in a science activity unless you are asked to.

Fill a glass with drinking water and put in two teaspoons of sugar. Don't stir. Taste a little from the top. Is it sweet? Hardly.

Now stir until the sugar has completely dissolved, and taste the top again. Now it's sweet. The sugar went in at the bottom, so if the top tastes sweet, the sugar must now be all through the water.

But look closely: can you see any sugar in the water? No. You can't see it, but you can taste it.

When sugar dissolves, it breaks up into its constituent particles, which can't be broken down any further. One tiny grain of sugar is made of millions and millions of them.

Activities 7.1 and 7.2 point to one big idea: matter is made of a huge number of extremely small particles, too small to see even with an ordinary microscope. When sugar dissolves, its tiny particles spread out and fit into the spaces between the water particles. The gaps between particles are called interparticle spaces.