Thursday, September 17, 2015

Measuring, Comparing, and Contrasting Matter

When practicing our ability to measure, compare, and contrast objects, we began by observing a group of objects and listing out their physical properties. Physical properties are simply the observable characteristics of an object. Then the students tested to see if each object was magnetic or not. After we recorded our results, we thought about characteristics that might make an object magnetic, and if those characteristics ALWAYS make an object magnetic. For example, is an object magnetic simply because it feels like it is made of metal? 

Next we moved to comparing matter based on volume, density, and states of matter. The students were given 6 vials containing mystery liquids (water, sand, cotton, baby oil, salt water, and air.) They found the mass of each vial in grams, then they found the volume of each container by measuring the water displacement after the vial was submerged in 200mL of water. Because all of our vials were the same, the vials should all have the same volume. Finally, the students put all six vials into a bucket of water to determine if they sink, float, or stay in the middle. What they found was that the vial of water floated in the middle. This led to a discussion of why. After lots of talking back and forth, the kids finally came to the conclusion that it was because the water in the vial has the same density as the water in which we put it. The sand and salt water sank because they are more dense than the water. The cotton, baby oil, and air floated on top because they are less dense than the water.

Our final discussion was led by these two questions: Does the state of matter affect whether an object sinks or floats? No, because we had solids that both sink and float and liquids that both sink and float. Does the mass affect whether an object sinks or floats? Yes, the higher masses sink, while the lower masses float.

Measuring Water Displacement
Density Test