Cloud Models: Solar Bag

By Selma Walsh on Mar 17, 2015

This activity is typically used to teach energy concepts and demonstrate how the sun warms air and makes air rise.  For visually impaired students, the bag can be a model for a cloud.  If we imagine peeling away the bag, the trapped air and water drops gathered in an area would represent a cloud.  Clouds are made of condensed water vapor, or many droplets of water.  The clouds float in the air around us.  Some clouds float very high (cirrus), while some clouds have so much water that they sink closer to the ground (stratus).   Clouds in the middle of the sky are referred to as “Alto” clouds. Clouds are named for their height above the ground and their shape.  A long flat cloud close the ground, like our solar bag, would be called “stratus” cloud.

Preparation:

15 minutes introduction, 30 minutes outside
 
Prior to going outside, explain the activity, discuss and model appropriate behavior.  You do not want students to try to chase the solar bag or grab and poke a hole or rip the bag.  Allow students to feel the deflated bag and string.

Materials

  1. Kite string (at least 100 feet).
  2. Large Solar Bag (These are available from Steve Spangler Science.)

 

Procedure

When teaching students with visual impairments, it is important to have structure and clear expectations:

Example:

We will walk outside in a single line.

children running around on the grass

  1. Sit on the curb in the same order that you walked outside.
  2. Stay seated until given permission to stand and touch the bag.
  3. Feel the bag with open hands.  Do not grab, pull or pinch the bag.
  4. Outside - Teacher ties one end of the solar bag and runs with one end open to capture air.  A fan could also be used to fill the bag with air as the bag sits across the students’ laps.
  5. Once air is in the bag, tie the other end with the remaining string.
  6. Allow the students to gently feel the bag, while it is low to the ground.  
  7. Wait for the sun to heat the bag (several minutes).
  8. Pull on the string and control the bag so that it floats just above the students’ heads.
  9. Allow the students to reach out and gently feel the bag.
  10. Help students take turns holding the string as the bag floats higher and higher.
  11. Repair any holes with packing tape, untie one end, and roll up for storage.

Safety Recommendations:

  1. Having the students sit on the edge of a curb and wait for the bag to come to them, prevents running, screaming and unsafe behaviors.
  2. Allow a few students at a time to stand, hold, and release the bag.
  3. Help one student at a time to control the string as the bag floats higher and higher, while the teacher never completely lets go of the control of the bag.

Inquiry Questions:

  1. What was inside the bag?
  2. What do you think makes the bag float?
  3. If we didn’t have a string, what could make the bag sink?

Connections:

  1. Observation of condensation activities, such as ice in a glass.
  2. Students add drops of water on a coin, waxed paper, or in the palm of their hand to see how water droplets stick together 
  3. Add drops of water to a cotton ball until it is absorbs enough water to drip (rain).
  4. Create models of clouds with cotton balls and glue on paper.
  5. Make shaving cream clouds floating in water.  Blow on the clouds to make them move and change their shape.
  6. Blow on various objects to make them move to show what air can do.
  7. Make “curly cues” and observe movement when exposed to heat.
  8. Observe 3D cloud models.

NGSS Standards:

K-ESS2-1.  Use and share observations of local weather conditions to describe patterns over time. 
K-ESS3-2.  Ask questions to obtain information about the purpose of weather forecasting to prepare for, and respond to, severe weather.
3-ESS2-1.  Use graphs and tables of local weather data to describe and predict typical weather during  typical weather in a  particular season in an area.
5-ESS2-1.  Develop a model using an example to describe ways the geosphere, biosphere, hydrosphere, and/or atmosphere interact.
MS-ESS2-4.  Develop a model to describe the cycling of water through Earth’s systems driven by Earth’s systems driven by energy from the sun and the force of gravity.
 
cloud models collage
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