Land is a limited resource used to meet the needs and wants of people. People often do not view land as a resource, comparable to water or air, but land use patterns reveal the ways people are using land to meet their needs and wants.

Land use patterns provide evidence of both individual and community choices. The methods to collect information about land use usually involve air photography, although land use is also mapped from direct observations. When an air photo is available, it is possible to identify, classify, and analyze land use patterns at the time the air photo was taken.

Air photos are compared with earlier air photos to assess change (as was done with Shelby Township in Lesson 1). Human impacts on land use are often quite sudden, while natural processes that impact land use are quite slow, with the exception of natural hazards and events such as wildfires or floods. One of the problems is being able to measure the amount of land affected by the changes. Scientists may use a dot planimeter to determine the amount of affected land.

The dot planimeter or dot grid method is a technique that does not require expensive equipment. Copy the dot planimeter onto a transparency. Then place it on the map with areas outlined to be measured. Count the dots located within the area being measured and total them. If the teacher wants to make some area comparisons from the map and the air photo, then it is possible to use commonly recognized spaces on Air Photo 1: Land Use and Land Cover: The Imprint of People. For example, the recreational space has four baseball diamonds in the lower center of the air photo. The four infields are easily recognizable.

Lay the dot planimeter on Air Photo 1: Land Use and Land Cover: The Imprint of People and place one dot on the center of the infield. Count the dot in the center and any other dots that fall on that same infield and that could represent a formula for thestudents to apply. In other words, those dots would represent an area about the size of a baseball infield. Keep in mind that this is a rough estimate, but the size of an infield is something that elementary students can usually associate with. There is a web site that teachers can refer to regarding the dot planimeter in the Additional Resources section that may be helpful in some ways.

The dot planimeter and the air photos used in this lesson have been sized so they are of the same dimensions. The dot planimeter has 100 dots. Students may use the dot planimeter to develop mathematical comparisons, such as 18 out of 100 dots are in open space while 37 of 100 dots are in residential. Alternatively, they may use percentages, such as 18% of land use is in open space while 37% of land use is in residential if those mathematical concepts have been taught earlier in the school year or in earlier grades.

Photography is widely used to obtain information. Real estate companies use photos of houses for sale to attract potential customers. Advertising of cars, rings, clothing, and furniture often include photographs. In this lesson the power of photography from the air is applied to land use. Just as students look at posters of people and places they like, they begin this lesson by making observations about posters. They will continue to use the skill of observation in subsequent lessons.