Science Assessment ~ Ideas ~ Processes that take place on the surface of the earth influence the composition and the temperature of the atmosphere.

Key Idea: Clouds and rain form as air cools and water vapor in the air condenses into water droplets.

Sub-Ideas
Items & Student Performance
Misconceptions
NGSS

Students are expected to know that:

Air cools as it rises away from the surface of the earth. Air can rise when 1) its temperature increases, 2) it is pushed upward as it moves over landforms (e.g., mountainsides), or 3) when it is pushed upward as the air encounters cooler (i.e., denser) air that wedges underneath the warmer air.
Clouds (including fog) can form anywhere that air cools. The lowering of air temperature can cause water vapor to condense such that the molecules of water that are part of the air form extremely tiny droplets of liquid water (or ice) in the air. The droplets that make up the clouds are not heavy enough to fall to the ground as precipitation.
As more droplets form in a cloud they collect together to form larger and heavier droplets. The droplets can eventually become heavy enough to fall toward the ground as rain, snow, sleet, or hail. The form of precipitation depends on the temperature of the air around the droplet.
The more water vapor there is in the air, the greater number of water droplets will form as the water condenses, making it more likely that visible clouds will form and that droplets will collect together and become heavy enough to fall as rain.
The cooler the air becomes, the more water will condense and form water droplets, making it more likely that clouds will form and that droplets will collect together and become heavy enough to fall as rain.

Boundaries:

Students are not expected to know the names and characteristics of specific types of clouds other than fog (e.g., they are not expected to know that some clouds are made of ice instead of water) or the conditions under which different types of clouds will form.
Students are not expected to know the term “dew point.”
Students are not expected to know that water droplets form around tiny solid particles of matter in the air or that droplets are more likely to form when there are more particles in the air.

Percent of students answering correctly (click on the item ID number to view the item and additional data)
Item ID Number	Knowledge Being Assessed	Grades 6–8	Grades 9–12
WC089002	Clouds can form anywhere, even far from bodies of water, because air with water in it can move into an area and form clouds.	57%	58%
WC076002	Molecules of water can be found in clouds and in air far away from clouds.	52%	60%
WC079002	Clouds are made up of tiny water droplets that form as water vapor in the air condenses.	54%	54%
WC083002	It will not rain if the tiny water droplets that make up clouds are not heavy enough to fall from the clouds.	48%	53%
WC081002	As cool air moves toward warmer air, the cool air can push the warmer air upward, which causes the warmer air to cool, condense, and form clouds.	41%	51%
WC091002	Clouds are likely to form as air moves up over a mountain because air cools as it rises and clouds are likely to form as air cools.	40%	50%
WC085002	Rain falls when tiny water droplets in clouds combine to form larger droplets.	41%	44%
WC080003	Rain forms as the air in a cloud cools, causing tiny water droplets to form and combine to form larger droplets.	35%	42%
WC084002	Rain falls from clouds when air cools, causing water droplets to form.	31%	49%
WC089001	Clouds form anywhere there is moist air that cools to form tiny water droplets.	40%	32%
WC082003	If two places have the same amount of water vapor in the air, rain is more likely to fall in the place where the air is cooler.	24%	30%

Frequency of selecting a misconception
Misconception ID Number	Student Misconception	Grades 6–8	Grades 9–12
WCM036	Clouds are like vessels that hold water (Moyle, 1980; Bar, 1989).	42%	35%
WCM039	A change in air temperature does not have an effect on whether clouds and fog form or rain falls (AAAS Project 2061, n.d.).	39%	35%
WCM113	Rain falls from a cloud when the pool of water in the cloud becomes too large, so the cloud can no longer hold the water inside (AAAS Project 2061, n.d.).	41%	30%
WCM063	There are water molecules in clouds, but not in the air outside of clouds (AAAS Project 2061, n.d.).	29%	25%
WCM038	Clouds are made of water vapor (AAAS Project 2061, n.d.).	23%	22%
WCM043	Clouds, fog, and rain form as air becomes warmer (Bar, 1989).	20%	20%
WCM066	The main cause of rain falling from clouds is wind blowing on the cloud and making the water in the cloud spill out (AAAS Project 2061, n.d.).	18%	16%
WCM111	Clouds need pollution in the air to form (AAAS Project 2061, n.d.).	9%	9%
WCM041	New clouds cannot form. Clouds are just pushed from place to place (AAAS Project 2061, n.d.).	9%	7%
WCM112	Rain falls from a cloud when two clouds collide, causing them to burst open (AAAS Project 2061, n.d.).	7%	7%

Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.

NGSS Statements
Code	Statement
ESS2.C MS	Water continually cycles among land, ocean, and atmosphere via transpiration, evaporation, condensation and crystallization, and precipitation, as well as downhill flows on land.