Hamilton County's two lowest performing high schools took opposite tracks when it came to 2021 graduation rates, numbers released by the Tennessee Department of Education show.

While Brainerd High School and The Howard School continue to struggle on state assessment tests, Brainerd improved its graduation rate to its highest level in five years but Howard's fell more than 6 percentage points.

Brainerd graduated 74.7% of its senior class in the spring, up more than 5% from two years ago but down 6.5% from three years ago. Meanwhile, Howard saw 66.8% of its seniors graduate, about the same as five years ago but up more than 3 percentage points from two years ago.

The roller-coaster scores indicate the difficulty in using graduation rates as the primary arbiter in a school's success, especially when assessment test scores languish similarly at both schools.

Overall, as noted in a Chalkbeat story carried by this newspaper Sunday, state graduation rates in 2021 fell almost 1% from 2020 to 88.7%, while those in Hamilton County dropped 1.5% to 85.5%.

In addition to Brainerd, five high schools (East Hamilton, Red Bank, Sale Creek, Sequoyah and Signal Mountain) increased their graduation rates from 2020, with Red Bank climbing 5.6 percentage points and Sale Creek 3.1 percentage points.

Among district schools whose rates were reported, five schools (Chattanooga School for the Arts and Sciences, Hamilton County Collegiate, Sale Creek, Signal Mountain and the STEM School) saw more than 95% of their seniors graduate, with CSAS (99%) and Hamilton County Collegiate and the STEM School (98.5% each) leading the way.

The fact that three of those five schools were magnet or speciality high schools indicates the importance of the district announcing earlier this month that it is offering students even more choices for the 2022-2023 academic year with 11 additional open enrollment schools, two additional Future Ready Institutes and a helpful Available Choice Lottery Seats page on the district website.

The district schools with the most consistent graduation rates over the past five years are Hamilton County Collegiate, Ooltewah and Signal Mountain. Rates have varied only 2.6% at Hamilton County Collegiate, while they have fluctuated only 3.2% at Ooltewah and Signal Mountain.

Making the biggest strides over the last five years are Lookout Valley, whose rate has increased 19.6%; Sale Creek, up 10.4%; Red Bank, up 10.3%; and Sequoyah, up 9.7%.

More disturbing are the schools whose 2021 graduation rates are lower than they were five years ago and those whose have seen their rates drop for two years.

The most recent classes at Central, Hixson, Soddy-Daisy and Tyner had lower scores their 2017 cohort, while East Ridge, Hixson, Ooltewah and Soddy-Daisy all have seen their rates drop for consecutive years since 2019.

(Technically, CSAS had a lower rate in 2021 than it did in 2017 — 99% as opposed to 100% — but it was a difference of one student not graduating in 2021. Also, Ivy Academy's graduation rates fell for two years since 2018, but its 2020 rates were not available from the state for comparison.)

While the state reported that 37 districts improved their graduation rates from 2020 to 2021, only one of those — Bradley County — is among the counties adjacent to Hamilton County. Rates there rose 3.1% from 91.6% to 94.7%.

The rest of the counties surrounding ours fell anywhere from less than one percentage point (Bledsoe and Marion) to as much as 6.3% in Rhea County and 9.4% in Sequatchie County. Rates for Meigs County in 2020 weren't available from the state, but that district fell only one percentage point from its 2019 rate.

It's hard to know what affect the COVID-19 pandemic had on graduation rates since schools with varying academic success over the last five years raised their rates, while many with modest success did not. Adding to the mix is that the pandemic caused the state to relax its graduation requirements in 2020 shortly after the pandemic set in.

The same is true with schools with large numbers of economically disadvantaged students. Locally, as mentioned earlier, Brainerd, with 85.5% economically disadvantaged students, raised its rates, while others did not. In four schools (East Ridge, Howard, Lookout Valley and Hamilton County Virtual School), the 2021 graduation rates of economically disadvantaged students were higher than the graduation rate for all students.

Meanwhile, the graduation rates for economically disadvantaged students at seven district schools fell from 2020 but increased in six others. The rates ranged from a high of 95.2% at Lookout Valley to a low of 54.5% in Hamilton County Virtual School.