Activities involve the microscopic examination of mushrooms and yeast. Decomposition - Students build a decomposition column and, using a microscope, examine the microorganisms growing in it. Over the course of many months, all organic material in the column is composted into humus. Local time and standard time are defined. Ratio - The ratio of the length to width of a rectangle is studied as an example of a characteristic property.
Students discover that all rectangles with the same length to width ratio are similar.
Seasons - Students study how the elevation of the sun effects the ratio of the height of a stick to the length of its shadow. They also observe how the elevation effects the amount of light reaching each square centimeter of the earth's surface. Clocks - Students measure the period of a pendulum for different values of its amplitude. The relevance of this to the history of clocks is explained. Top Description of Grade 7 Units Measurement and ratios, introduced in sixth grade, are used with increasing sophistication in seventh grade.