## Thursday, August 5, 2010

### Rate of Solution: Sugar Cubes

I did this with 4th grade students who were learning about solutions. It's simple, but they have a good time and learn a little something in the process!

For each pair of students, you'll need:
-Cup/Beaker
-4 Sugar Cubes
-Spoon
-Stopwatch

For the whole class:
-Hot Water
-Room Temperature Water
-A means of crushing sugar cubes

Provide each pair of students with a cup (clear is better - it's hard to see a white sugar cube in a white cup) of room temperature water.

Have them drop a whole sugar cube into the water and time how long it takes for the cube to dissolve (no stirring).

This is their baseline measurement. They'll now test several variables, one at a time.

With a fresh cup of room temperature water, drop in a whole sugar cube and time how long it takes for it to dissolve when you STIR it.

With another fresh cup of room temperature water, drop in a CRUSHED sugar cube and time how long it takes to dissolve (no stirring).

Get a cup of HOT WATER, drop in a whole sugar cube and time how long it takes to dissolve (no stirring).

There are several ways to conclude this experiment. Try one or more...
1 - Have students create bar graphs of the data:
-Room Temperature water vs. hot water
-Stirring vs. not
-Crushed cube vs. whole cube

2 - After students have analyzed their data, have them race to see who can dissolve their sugar cube the fastest. They've got three choices to make: hot or room temperature water, will they stir or not, and will they use a crushed cube or a whole cube.

3 - Along the same lines as #2, have a contest where students try to prevent a sugar cube from dissolving for as long as possible.