Formative Assessment

Have your students collected accurate weight and volume data that they use to support a claim about what happens to salt when it dissolves in water?

Look for evidence in the notebook entries. What happens when salt dissolves in water? Without accurate data, students will be unable to support claims that dissolved salt is present in the water even though it’s invisible.

Use these criteria to interpret students’ work:

• Is the weight of water alone plus the weight of the salt added equal to the weight of dissolved salt and water?
• Does the drawing of volume data show that adding salt increases the water level?

Once students have collected and recorded accurate data, the next step is to ask them to make claims about whether dissolved salt still exists in the water even though you can no longer see it, and to use the weight and volume data they just collected to support their claims.