Capacity is defined as the number of students a building can house at any given time. In order to calculate capacity, there are a number of factors that must be assessed; we developed our capacity analysis by asking and answering a series of questions. It is important to note that the capacity numbers are fluid, and that they depend on answers to the questions listed below:
- How many buildings do we have available for students (for the original analysis, buildings were coded to their original design use: elementary, middle, or high school)?
- Elementary (K-5): 67 +3 Interim Sites
- Middle (6-8): 17 +1 Interim Site
- High (9-12): 10 +1 Interim Site
- How many classrooms do we have available in these buildings, including on-site portables?
Using floor plans, a building survey, and enrollment reports, we determined both the number and type of teaching stations in each building. Teaching stations are divided into six categories: average, small, special program, gymnasium, arts/science, and computer labs.
- Elementary: 1,855
- Middle: 934
- High: 794
- On average, how many students should we plan for in each classroom?
The capacities listed below are called "planning" class sizes for the purpose of the capacity analysis. We established a specific class size for each type of room listed in step B, in order to be as accurate as possible for each individual building.
- Elementary:
- Kindergarten through 3 rd grade: 23
- 4th thru 5 th grade: 25
- Middle (6-8): 28
- High (9-12): 30
- How many students can we serve in our building?
Multiplying the teaching stations listed in part B by the appropriate "planning" class sizes listed in part C shows that we can serve the following number of students (this does not include the capacity in interim sites):
- Elementary: 25,775
- Middle: 14,484
- High: 13,880
- What do we anticipate our enrollment will be in the future (based on 2014 projections, which does not include non-resident students)?
- Elementary: 21,972
- Middle (6-8): 9,580
- High (9-12): 12,266
We included all open school buildings, regardless of current use. Based on this analysis, we determined that Seattle Public Schools has an excess capacity of 8,893 seats now, and we project this number to increase to 10,320 by 2014. (It is important to note that capacity differences may fluctuate with programmatic changes at individual buildings).
We use the term "set-aside" to refer to the seats in a school that are reserved for students with special needs, such as Special Education and Bilingual students, who are frequently in classrooms that require special services or extra space. We included set-aside seats when we determined that the school district has excess capacity.
In order to account for teaching stations that may have classes smaller in size than the "planning" class sizes (discussed in Question #1), or that have other uses besides classrooms, the building's total capacity is set at only 75 percent of the actual capacity - so an average of 25 percent is used for set-aside seats.
The current usage of each building is a key component in determining the "planning" class size, the inventory of existing teaching stations, and the percentage of capacity to use as set-aside seats. Using enrollment reports that show students by homeroom, we can determine how schools are currently using their teaching stations in terms of the number of students and the types of services (e.g., bilingual, special education, and advanced learning) in individual classrooms.
As discussed in the response to Question #2, we determined that about 25 percent of a building's total capacity would be adequate for set-aside seats for special services or programs. In addition, the detailed inventory of all activities in each building will be used as part of the implementation process for any board-approved closures or consolidations.
We use the term "demographics" to mean the size, distribution, and characteristics (e.g. age, race, and income) of a population.
We refer to the City of Seattle's population projections when we develop our enrollment projections. Specifically, we consider expected changes in the number and types of people and housing in the City when making assumptions about trends in births and capture rates.
Each month, we also receive an extract of permits that shows the number and type of housing units by address. We use this data as one component in forecasting the total number of school-age children in each area of town.
The goal in population forecasting is to develop a model that minimizes errors by including factors that have been shown to be predictors of enrollment patterns. We make predictions based on extensive research and testing, while considering the following:
- Enrollment in Seattle Public Schools has fluctuated considerably in the past, and has been declining since 1999. The number of students attending Seattle Public Schools in 2014 is projected to be slightly lower than the current enrollment.
- The City of Seattle has grown by more than 50,000 in the last 20 years, while enrollment in Seattle Public Schools has decreased by 10,000.
- The percentage of school-age children as a component of the total population has been decreasing over the last 20 years.
The "underlying population" refers to the number of school-age children living in an area. When we create school attendance boundaries, we will use both the current and projected underlying populations to make sure each school's capacity can accommodate its neighborhood students.