A few weeks ago, a client called while looking at properties in Centreville. They mentioned that the online score for Centreville Elementary School was 8 out of 10, so they felt reassured and prepared their deposit. However, after visiting the open house and talking to other parents in the area, they realized it was a bit different from what they expected. The score was clearly 8, but why did the on-site feeling differ?

Here, we need to address how GreatSchools scores are created. The scores ranging from 1 to 10 that appear on Zillow or Redfin are ratings given by a nonprofit organization called GreatSchools. Elementary and middle schools reflect two main factors equally. One is the test scores for that year, and the other is academic growth, which measures how much students have improved compared to the previous year. For high schools, college readiness is added, and the three categories are each weighted one-third.

The problem is that looking at just one combined number from these two factors does not reveal what contributed to the high score. There may be schools with high test scores but relatively low growth indicators. Conversely, there are schools with average test scores but consistent improvement in student performance each year. If you make a decision based solely on the number 8, you might miss the combination of factors behind it.

In fact, there is quite a variance in scores among elementary schools around Centreville. According to GreatSchools, Centreville Elementary School has a score of 8, Cub Run Elementary School has 7, Bull Run Elementary School has 6, and both Centre Ridge Elementary School and Virginia Run Elementary School have 5. The reason for these differences within the same Fairfax County is that factors like test scores, student-to-teacher ratios, and recent growth trends vary from school to school.

Therefore, it is essential to look at the detailed categories next to the scores. When you open the GreatSchools page, subcategories like Test Scores, Student Progress, and Equity are displayed separately. The Equity category shows whether students from diverse backgrounds are achieving good results equally. Even if the overall score is high, if one of these subcategories is particularly low, it is important to check the reason first.

Another point to consider is that GreatSchools scores are updated annually based on performance data released by the state government. This means that if a new principal has taken over or programs have changed, there may be a lag before those changes are reflected in the scores. The difference in impression felt at the open house and the online score could also be due to this lag.

Additionally, there are a few more things to verify. Check whether the student-to-teacher ratio is not higher than the county average, whether the rating has been trending upward or downward over the past three years, and whether the parent reviews are recent or outdated. Scores are typically calculated based on test data from one to two years ago, so if the school situation has changed recently, it may not yet be reflected in the scores.

Finally, the most commonly overlooked aspect is which school your home address is actually assigned to. It is not uncommon for the school listed on real estate websites to differ from the actual assigned school. School district boundaries can be adjusted by the county school board as needed, so they may change over time. If you find a property you like, please verify the assigned school with the exact address on the Fairfax County Public Schools website.

Rather than judging a school based on a single score, developing the habit of breaking down the elements that make up that score ultimately reduces regrets. This article is not investment or legal advice, and it is advisable to consult with a professional regarding school district and tax-related matters before making any agreements.