You'll find kids playing on the playground, searching through the library or mingling at lunch. But when you look into the classrooms you'll notice something very different. Boys are with boys and girls are with girls.
"(It's) incredibly successful looking at our data and looking at data across the country," Principal Robin Gilbert said.
According to Gilbert, teachers came up with the idea while researching ways to elevate boys reading and language arts scores. That's where the idea of offering same sex classrooms came from.
"Brain research shows boys brains develop in a different pattern, not a better pattern but a different pattern than a girl's brain," Gilbert said. "A 6-year-old boys brain is more similar to a 10-year-old boy's brain than it is to a 6-year-old girl's brain."
Historically boys scored, on average, about 10 points below the girls on standardized testing and girls underperformed in math and science. But now, six years after starting the program, school officials are happy to see the latest test results.
Girls are now only 0.7 percent below the boys in math. Boys are only 0.5 percent behind girls in language skills and actually beat the girls by 2.1 percent on the latest reading exam. No one can remember the last time that has happened.
Critics aren't convinced by the numbers saying there are too many variables to say a shift in test scores is due to the same sex classroom environment. They also say same sex classrooms reinforce stereotypes. Principal Gilbert disagrees.
"We're seeing just the opposite," Gilbert said. "Those stereotypes are being taught within mixed gender classrooms and girls are learning, 'I just don't do math well, my mother didn't do math well,' and they're learning that. So when we can have them in a single gender classroom we can break those stereotypes and teach them to be scientists."
"Under Title 9 it's pretty specific what classrooms cannot do this voluntarily for some and not for others," ACLU spokesperson Monica Hopkins said.
ACLU Idaho opposes single sex classrooms and it's sent a letter to Middleton Heights School Leaders.
"You know we respectfully request that at the end of the school year you stop all sex segregated classrooms unless they comply under Title 9," Hopkins said.
Middleton Heights Elementary gives students what it calls "companion materials" to supplement required coursework. Boys get it in reading and language and girls get extra materials in math and science. That's where the issue lies with the ACLU.
"The reason that the Middleton Heights Elementary School implemented sex segregated classrooms in the first place was to raise boys reading standards. That is not an equal objective. The equality under Title 9 is that you raise the standard for all students, not just say boys need their standard raised," Hopkins said.
Middleton parents are upset at the news the ACLU is now involved and want to shut down same sex classrooms.
"This school is helping kids learn and enjoy learning. It's not to separate them," parent Maria McCain said.
"I'm just surprised that they're (ACLU) is complaining about the effectiveness of the classrooms. I think that's one of the important things about education, try to improve and if it's effective then why not do it?" parent Al Mendiola said.
"I think what it comes down to is we have a choice," parent Liz Mendiola said.
For now, same sex classrooms at Middleton Heights Elementary are safe. But if school leaders continue offering the program, they might end up in court
"Middle Heights Elementary School is aware of the problem and they have an opportunity and we've requested of them that they stop this program so as to not be the subject of a court battle to stop them from implementing the segregation in the classrooms," Hopkins said.
"Most schools across the country that receive these letters shut down the programs. Schools are public funding. How much money can you spend battling a name like the ACLU. It can be intimidating and it can be scary. I do care if it's legal and I very much care if it's effective - that's my job," Gilbert said.