Geyserville Unified: science

The shaded band is this district's normal range. If nothing about how it works changes, nearly every future year should land inside it. Zero means the typical student just meets the state standard. The small numbers under the years are how many students were tested.

Step 1 · Each year's result

For each grade tested, take the average (mean) scale score from the California Department of Education's results file, and subtract the lowest score that counts as "Standard Met" for that grade. That is the grade's distance from standard. Weight each grade by its share of the students tested, then add the grades up. Grades where the state hides the average because ten or fewer students tested are left out entirely.

2019 from cast_ca2019_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
5	25,416	196.2	− 214	−17.8	× 18 / 57	−5.6
8	25,417	392.2	− 415	−22.8	× 19 / 57	−7.6
10	25,418	588.2	− 615	−26.8	× 20 / 57	−9.4
Sum, rounded to a whole point						−23

2022 from cast_ca2022_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
5	31,536	203.8	− 214	−10.2	× 12 / 77	−1.6
8	31,537	382.9	− 415	−32.1	× 15 / 77	−6.3
10	31,538	597.9	− 615	−17.1	× 13 / 77	−2.9
11	31,539	583.1	− 615	−31.9	× 20 / 77	−8.3
12	31,540	598.6	− 615	−16.4	× 17 / 77	−3.6
Sum, rounded to a whole point						−23

2023 from cast_ca2023_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
5	31,500	189.5	− 214	−24.5	× 14 / 29	−11.8
8	31,501	384.5	− 415	−30.5	× 15 / 29	−15.8
Sum, rounded to a whole point						−28

2024 from cast_ca2024_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
5	31,568	201.3	− 214	−12.7	× 15 / 43	−4.4
8	31,569	386.1	− 415	−28.9	× 14 / 43	−9.4
11	31,570	604.4	− 615	−10.6	× 14 / 43	−3.5
Sum, rounded to a whole point						−17

2025 from cast_ca2025_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
5	31,555	196.1	− 214	−17.9	× 19 / 48	−7.1
8	31,556	405.4	− 415	−9.6	× 15 / 48	−3
11	31,557	596.1	− 615	−18.9	× 14 / 48	−5.5
Sum, rounded to a whole point						−16

2026 from cast_ca2026_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
5	31,369	199.3	− 214	−14.7	× 15 / 43	−5.1
8	31,370	386.8	− 415	−28.2	× 13 / 43	−8.5
11	31,371	592.4	− 615	−22.6	× 15 / 43	−7.9
Sum, rounded to a whole point						−22

Step 2 · The average and the normal range

Average: add the yearly results and divide by how many there are. −23, −23, −28, −17, −16, −22 → −21.5
Typical year-to-year change: how far the result moved from each year to the next, ignoring up or down. 2019→2022: 0 · 2022→2023: 5 · 2023→2024: 11 · 2024→2025: 1 · 2025→2026: 6 → average 4.6
Normal range: multiply the typical change by 2.66, then add it to the average and subtract it. 4.6 × 2.66 = 12.2. Upper limit −9.3, lower limit −33.7.

Why 2.66? It is the standard factor from quality control, the work of Walter Shewhart and W. Edwards Deming. It turns "how much the result typically changes in a year" into "how far it can wander by chance alone".

Years with no result (no state tests were given in spring 2020) are skipped: the year-to-year change runs from the last year with a result to the next one.

Step 3 · Free or reduced-price meals

The share of enrolled students eligible for free or reduced-price meals — for a district, the total across its schools. From 2014–15, 2015–16, 2016–17, 2017–18, 2018–19, 2020–21, 2021–22, 2022–23, 2023–24, 2024–25, 2025–26.

Geyserville Unified