Collect observable data from students about their home 2-bottle systems. As students respond, record their observations for reference during the Make meaning discussion

Where did you see water or drops of water?

• A larger area of the inside surface of each bottle is now covered with drops.
• A puddle may be starting to form in the upper bottle.

Where are there no drops of water?

• There is a large area with no drops directly under the light.
• Smaller sections of the lower and upper bottles may have no drops of water.

What is the warmest part of the 2-bottle system?

• The warmest part is the portion of the lower bottle that is directly under the light.