Key Idea: The amount of time any place experiences daylight varies over the course of a year, and the farther a place is from the equator the greater the variation is.

Students are expected to know that:

  1. The amount of time that the sun is visible in the sky above any given place over a day changes over the course of a year. In late June in the northern hemisphere the sun rises above the horizon earlier than any other day and sets later than on any other day such that at any place in the northern hemisphere the sun is above the horizon for the longest period of time for the year. The sun gradually rises above the horizon later and moves below the horizon earlier until late December, when the number of daylight hours gradually starts increasing again until late June. The same pattern, where the longest day is at the beginning of the summer (late December) and the shortest day is at the beginning of the winter (late June), occurs in the southern hemisphere.
  2. The length of day varies different amounts at different places on the surface of the Earth. At the equator, the length of day does not vary over the course of the year. The farther a place is north or south of the equator, the more the length of day increases from winter to summer and decreases from summer to winter.
  3. The length of time during which the sun is in the sky above any given place influences the amount of energy sunlight can transfer to that place. The longer sunlight shines on a place, the more energy it transfers to it over the course of a day.
Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

CLM027

The equator always has the most hours of daylight, and the north pole always has the fewest hours of daylight (AAAS Project 2061, n.d.).

35%

35%

CLM026

The number of hours of daylight on a given day is the same everywhere on earth (AAAS Project 2061, n.d.).

15%

13%

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.