"He was trying to figure out whether I was black or white, and he looked at me, and he said, 'You know what; you're a smart kid; I'm going to check white,' " said Sidner, whose mother is a white British woman and whose father is African-American.

"It definitely had an impact on me," she said. "It made me want to fight back and say, 'I can be black and smart. Those are not separate entities. Those are not different things.' "

It turns out that when black and Latino middle school students notice racial bias at school, they are more likely to lose trust in their teachers and other authority figures, according to a study published in the journal Child Development this week.

The study also showed how establishing trust in their teachers can have life-long consequences for middle school students, even making a significant difference in their likelihood of attending college, said Geoffrey Cohen, a professor at the Stanford Graduate School of Education and a co-author of the study.

"There's this kind of hidden construct of trust that teachers and schools are influencing all the time and maybe not knowing it, and they have these far-off, far-flung consequences, like college enrollment," Cohen said.

"A lot of the things that happen to us during our teenage years end up sticking with us. A disproportionate number of our memories, for instance, come from our teenage years. If you suffer a depressive episode in your teen years, you're more likely to suffer one later on in adulthood," he said. "This developmental stage is important."

Trust linked to success in school

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The study involved 277 middle school students in Connecticut who were surveyed twice yearly about their perceptions of school from sixth to eighth grade, and then were tracked to indicate whether they enrolled in a four-year college after high school. About half of the students were white, and about half were black. Their teachers were white.

The researchers assessed each student's trust in school by including statements in the survey such as "I am treated fairly by teachers and other adults at my school" or "students in my racial group are treated fairly by teachers and other adults." The students could select whether they agreed or disagreed with each statement.

The survey results showed that while the trust students had in their teachers declined from sixth to eighth grade overall, that trust plunged faster for black students and had a more significant association with their likelihood of attending college.

Among black students, when their trust in school declined, their rate of college enrollment was about 43%, but when their trust increased, it was about 64%, said David Yeager, an assistant professor of developmental psychology at the University of Texas at Austin and lead author of the study. So, there was a difference of 21 percentage points.

Among white students, when their trust declined, their rate of college enrollment was about 54%. When trust increased, college enrollment was about 62%. So, there was a difference of only 8 percentage points, Yeager said.

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The researchers also surveyed 206 middle school students in Colorado over a one-year period. About half of the students were white, and about half were Latino. Their teachers were white.

The surveys showed that a loss of trust was more significant among the Latino students and emerged more prominently in the seventh grade.

But the study has some limitations.

"I would love to see researchers try to replicate that sort of 'trust gap' in other schools and see if they get it. We only looked at two schools," Cohen said.

"How general it is, is a question. I think it's general for two reasons. One is, it does match with other research," he said. "The second reason is that these two schools, they're pretty different. They're from different regions in the United States. One is the Mountain West; one's in Connecticut."

Is there a flaw in the education system?

Middle school, a time when adolescents are carving out their identities, may be when a student needs encouragement from a trustworthy authority figure the most.

Photos: What's inside those backpacks? Photos: What's inside those backpacks? Clarke, kindergarten, 2.2 pounds – CNN asked dozens of Atlanta students to open up their backpacks and reveal: What, exactly, is in those big, heavy bags? Here's what we found.



Clarke, a kindergarten student at KIPP STRIVE Primary, said her favorite subject is "playing outside and learning stuff." Hide Caption 1 of 33 Photos: What's inside those backpacks? Paris, kindergarten, 1.6 pounds – Paris, a kindergarten student at KIPP STRIVE Primary, said she's just like Rarity, one of the My Little Pony characters on her backpack. "She's so fancy," Paris said. Hide Caption 2 of 33 Photos: What's inside those backpacks? Jahi, first grade, 2.2 pounds – Jahi, a student at KIPP STRIVE Primary, said he didn't want to carry his crayons anymore. "My mom took care of them because I said it was sooooo heavy," he said. Hide Caption 3 of 33 Photos: What's inside those backpacks? Ashe, first grade, 3 pounds – Ashe, a first-grade student at KIPP STRIVE Primary, said her folder was the most important thing in her backpack. Hide Caption 4 of 33 Photos: What's inside those backpacks? Lawrence, second grade, 0.7 pounds – Lawrence, a second-grade student at KIPP STRIVE Primary, said he's a huge sports fan, so he most often uses his book from Mike Lupica's "Comeback Kids" series. Hide Caption 5 of 33 Photos: What's inside those backpacks? Aniyah, second grade, 1.1 pounds – Aniyah, a second-grade student at KIPP STRIVE Primary, said her homework folder is the item she uses most. Hide Caption 6 of 33 Photos: What's inside those backpacks? Dylan, third grade, 5 pounds – Dylan, a third-grade student at Westminster Lower School, said he wants to stop carrying his heavy "Harry Potter" book, but he liked having double-sided tape on hand in case he wants to build something. Hide Caption 7 of 33 Photos: What's inside those backpacks? Noah, third grade, 8.9 pounds – Noah, a third-grade student at KIPP STRIVE Primary, said, "It feels like I'm carrying a 100-pound baby, but the stuff comes in really handy." If he could leave anything behind? "Probably one of my flashlights." Hide Caption 8 of 33 Photos: What's inside those backpacks? Brenner, fourth grade, 5.6 pounds – Brenner, a fourth-grade student at Westminster Lower School, said he didn't want to leave anything from his backpack behind, whether it is his books or his National Geographic cards. Hide Caption 9 of 33 Photos: What's inside those backpacks? Arav, fourth grade, 1.5 pounds – Arav, a fourth-grade student at Westminster Lower School, said he wanted to stop carrying some books because they make him feel like he's falling, but he still needs his agenda and spare headphones. Hide Caption 10 of 33 Photos: What's inside those backpacks? Jaia, fourth grade, 11.4 pounds – Jaia, a fourth-grade student at Westminster Lower School, said she often carries her keychain collection and books, as well as her cello. Hide Caption 11 of 33 Photos: What's inside those backpacks? Alexa, fifth grade, 5.5 pounds – Alexa, a fifth-grade student at Westminster Lower School, said art is her favorite class and it doesn't require her to carry many supplies. She wishes she could stop carrying her physical education clothes, especially while they're working on swimming. Hide Caption 12 of 33 Photos: What's inside those backpacks? Caroline, fifth grade, 8.6 pounds – Caroline, a fifth-grade student at Westminster Lower School, said she uses the book she's reading for fun more than anything else. She'll pull it out every time she has a quiet moment between classes or while she's waiting for her part in chorus. Hide Caption 13 of 33 Photos: What's inside those backpacks? Raina, sixth grade, 17.6 pounds – Raina, a sixth-grade student at KIPP WAYS Academy, said she wished she could leave her binders behind, but she takes them home so she can study more. Hide Caption 14 of 33 Photos: What's inside those backpacks? Jeremiah, sixth grade, 18.8 pounds – Jeremiah, a sixth-grade student at KIPP WAYS Academy, said a pencil is the most used item in his backpack, but he still has to carry his homework folder and an extra binder "for emergencies." Hide Caption 15 of 33 Photos: What's inside those backpacks? Aaliyah, seventh grade, 7.1 pounds – Aaliyah, a seventh-grade student at KIPP STRIVE Academy, said her SpongeBob SquarePants backpack is "perfectly fine," but she wishes she didn't have to carry her cheer practice clothing. Hide Caption 16 of 33 Photos: What's inside those backpacks? Jordan, seventh grade, 13.4 pounds – Jordan, a seventh-grade student at KIPP Strive Academy, said his backpack was twice its current size when he was in fifth grade. Now, he mostly uses his homework folder and a clipboard so he can work on the bus. Hide Caption 17 of 33 Photos: What's inside those backpacks? Amber, eighth grade, 11.9 pounds – Amber, an eighth-grade student at KIPP STRIVE Academy, said she's not allowed to use her iPad at school, but she can't leave it behind because she uses it "for everything." Still, she has to carry her notebooks and books. Hide Caption 18 of 33 Photos: What's inside those backpacks? Oliver, eighth grade, 8.6 pounds – Oliver, an eighth-grade student at KIPP STRIVE Academy, said his backpack is heavy, "but not to the point where it's ridiculous." Still, several weeks into the school year, he was still carrying most of his class binders instead of using his locker. Hide Caption 19 of 33 Photos: What's inside those backpacks? Trey, ninth grade, 18.1 pounds – Trey, a ninth-grade student at Westminster Upper School, said he wishes he could stop carrying his math book. Most material can be found online, he said. Hide Caption 20 of 33 Photos: What's inside those backpacks? Isabella, ninth grade, 24 pounds – Isabella, a ninth-grade student at Westminster Upper School, said she's gotten used to carrying a heavy backpack, but she would rather use her computer than bulky textbooks. Hide Caption 21 of 33 Photos: What's inside those backpacks? Alex, 10th grade, 19 pounds – Alex, a 10th-grade student at Westminster Upper School, said he wishes he could stop carrying his French book, although his teachers have generally tried to cut back on books. Last year, he said, students used an online version. Hide Caption 22 of 33 Photos: What's inside those backpacks? Chinara, 10th grade, 8.8 pounds – Chinara, a 10th-grade student at KIPP Atlanta Collegiate, said chemistry is her favorite class and she wishes she could stop carrying her notecards for studying world history. Hide Caption 23 of 33 Photos: What's inside those backpacks? Meghna, 10th grade, 21 pounds – Meghna, a 10th-grade student at Westminster Upper School, said she purchased an online textbook for her favorite class, chemistry, but most courses don't offer a digital book. Hide Caption 24 of 33 Photos: What's inside those backpacks? Brandon, 11th grade, 12.4 pounds – Brandon, an 11th-grade student at KIPP Atlanta Collegiate, said he uses the binder for his favorite class, honors U.S. history, more than anything in his bag. But it also takes up the most space in his backpack, he said. Hide Caption 25 of 33 Photos: What's inside those backpacks? Allie, 11th grade, 23.5 pounds – Allie, an 11th-grade student at Westminster Upper School, said it's tough to get back to her locker between classes, so she tends to carry everything she might need with her, including her script for the musical "Titanic." Hide Caption 26 of 33 Photos: What's inside those backpacks? Elijah, 11th grade, 30 pounds – Elijah, an 11th-grade student at KIPP Atlanta Collegiate, said he never uses his locker. He prefers to keep books for his Advanced Placement and honors courses with him in case he has a few minutes to get some homework done while he's still at school. Hide Caption 27 of 33 Photos: What's inside those backpacks? Myles, 11th grade, 17.1 pounds – Myles, an 11th-grade student at Westminster Upper School, said he stopped carrying his cello home most days and stopped carrying his computer in order to lighten his load. Still, he has to carry his history book all the time -- there's reading to do every night. Hide Caption 28 of 33 Photos: What's inside those backpacks? Tyler, 11th grade, 19.2 pounds – Tyler, an 11th-grade student at Westminster Upper School, said he uses his laptop most often, and he wishes he could stop carrying his history and math books. Hide Caption 29 of 33 Photos: What's inside those backpacks? Erickie, 12th grade, 19 pounds – Erickie, a 12th-grade student at KIPP Atlanta Collegiate, said math is his favorite subject and his calculus book is probably the item he uses most from his backpack -- but it's also the one he wishes he could stop carrying. "It weighs the most," he said. Hide Caption 30 of 33 Photos: What's inside those backpacks? Berhan, 12th grade, 15 pounds – Berhan, a 12th-grade student at Westminster Upper School, said she often carries her art board around with her as well (not pictured), as art is one of her favorite classes. Hide Caption 31 of 33 Photos: What's inside those backpacks? Tyler, 12th grade, 13 pounds – Tyler, a 12th-grade student at Westminster Upper School, said he uses his computer more than anything else in his backpack. He carries less now than he did as a freshman, he said. Hide Caption 32 of 33 Photos: What's inside those backpacks? Sherrell, 12th grade, 10.3 pounds – Sherrell, a 12th-grade student at KIPP Atlanta Collegiate, said she loves reading and writing, and she uses her laptop daily to write college essays and look for scholarships. But if she could stop carrying anything? "The whole bookbag," she said. Hide Caption 33 of 33

said Chris Emdin, associate professor at Columbia University's Teachers College and author of the book " Yet, in most middle schools, such encouragement is lacking -- and that might be because standardized exams are higher-stakes starting around then,said Chris Emdin, associate professor at Columbia University's Teachers College and author of the book " For White Folks Who Teach in the Hood ... and the Rest of Y'all Too ."

"It's part of elementary school practice for young people to feel like the teachers love them and to feel as though, 'you're valuable. You're smart.' It's almost like part of the discourse in elementary education," said Emdin, who was not involved in the new study.

"But when you get to middle and high school, the focus becomes less on the social and emotional development of the learner and more of an emphasis on the content area," he said. "What's flawed about the system is that, at the point where youth are most vulnerable in carving out their identities is the point where teachers are least prepared to help in developing trust and confidence. So it's at that age that we need to sort of really infuse practices that let kids know how much they are loved and how brilliant they are."

Once a teacher affirms a child's abilities, that child is more likely not only to believe in his or her own abilities but to trust that teacher, Emdin said.

He added that students, especially those of color, thrive when they feel as if a teacher cares about them, is consistent in what and how they are teaching, and is someone students can trust.

"For young people, care, consistency and trust are the anchor of being engaged academically. If any of those three things are missing, then you can't engage them," Emdin said.

"So teachers have to be able to exhibit care, and they have to be consistent in the things that they tell young people," he said. "If that happens, then young people feel like they can be trusted, and then that opens up a whole new world of possibilities."

'We can have more influence than we think'

For the new study, researchers also tested whether an intervention could improve trust in the teacher-student relationship.

At the same school in Connecticut where the researchers assessed a trust gap, 88 white and black seventh-graders were given a handwritten letter from their teacher, along with feedback comments on an assignment they completed.

Half of the students received a letter stating, "I'm giving you these comments so that you'll have feedback on your paper."

The other half received a letter stating, "I'm giving you these comments because I have very high expectations and I know that you can reach them."

The students and the teacher were unaware of who received which type of letter.

Photos: Children's books about diversity Photos: Children's books about diversity Books to teach children about diversity – Picture books can be useful tools to help young children learn about race and diversity how to deal with bias and bullying and how to be an ally to others. The Human Rights Campaign's Welcoming Schools program publishes reading lists for educators and parents interested in starting those discussions. Here are several of their recommendations, including Kadir Nelson's "I Have A Dream," which honors the memory of the Rev. Martin Luther King Jr. Hide Caption 1 of 16 Photos: Children's books about diversity Books to teach children about diversity – "The Sneetches and Other Stories," by Dr. Seuss, includes the story of creatures tricked into seeing only the differences among themselves -- and learning to see what they have in common. Hide Caption 2 of 16 Photos: Children's books about diversity Books to teach children about diversity – "Teammates," written by Peter Golenbock and illustrated by Paul Bacon, tells the story of Jackie Robinson, the first black ballplayer in the major leagues, and his white teammate, Pee Wee Reese. Hide Caption 3 of 16 Photos: Children's books about diversity Books to teach children about diversity – "Marisol McDonald Doesn't Match/Marisol McDonald no combina," written by Monica Brown and illustrated by Sara Palacios, tells the story of a girl with red hair and brown skin, a Peruvian-Scottish-American who is perfectly happy the way she is. Hide Caption 4 of 16 Photos: Children's books about diversity Books to teach children about diversity – "Happy Birthday, Martin Luther King Jr.," written by Jean Marzollo and illustrated by J. Brian Pinkney, celebrates the life of the civil rights leader. Hide Caption 5 of 16 Photos: Children's books about diversity Books to teach children about diversity – "All the Colors of the Earth," by Sheila Hamanaka, explains the shades of skin through the color tones of the Earth. Hide Caption 6 of 16 Photos: Children's books about diversity Books to teach children about diversity – "Zero," by Kathryn Otoshi, introduces ideas about body types and social interactions amid lessons about counting and numbers. Hide Caption 7 of 16 Photos: Children's books about diversity Books to teach children about diversity – "Each Kindness," written by Jacqueline Woodson and illustrated by E.B. Lewis, tells the story of a girl who teases another student until, eventually, that girl stops coming to school. Hide Caption 8 of 16 Photos: Children's books about diversity Books to teach children about diversity – "Across the Alley," written by Richard Michelson and illustrated by E.B. Lewis, tells the story of an African-American child and Jewish child who develop a secret friendship. Hide Caption 9 of 16 Photos: Children's books about diversity Books to teach children about diversity – "The Skin You Live In," written by Michael Tyler and illustrated by David Lee Csicsko, offers vivid illustrations and descriptions of skin colors. Hide Caption 10 of 16 Photos: Children's books about diversity Books to teach children about diversity – "Crossing Bok Chitto: A Choctaw Tale of Friendship and Freedom," written by Tim Tingle and illustrated by Jeanne Rorex Bridges, follows the friendship of a Choctaw girl and an enslaved African-American boy. Hide Caption 11 of 16 Photos: Children's books about diversity Books to teach children about diversity – "Shades of People," by Shelley Rotner and Sheila Kelly, is a photography book that shows the variety of physical traits people have. Hide Caption 12 of 16 Photos: Children's books about diversity Books to teach children about diversity – "My Name is Bilal," written by Asma Mobin-Uddin and illustrated by Barbara Kiwak, is the story of a boy teased by his classmates for being Muslim, and wondering if he should go by another name, Bill. Hide Caption 13 of 16 Photos: Children's books about diversity Books to teach children about diversity – "Crow Boy," by Taro Yashima, tells the story of a boy rejected at school, and a kind teacher who helps him find acceptance. Hide Caption 14 of 16 Photos: Children's books about diversity Books to teach children about diversity – "Our Children Can Soar: A Celebration of Rosa, Barack, and the Pioneers of Change," by Michelle Cook, is "part historical, part poetry, and entirely inspirational," as it takes readers through the U.S. civil rights movement, Welcoming Schools says. Hide Caption 15 of 16 Photos: Children's books about diversity Books to teach children about diversity – "Desmond and the Very Mean Word," written by Desmond Tutu and Douglas Carlton Abrams and illustrated by A.G. Ford, is based on a story from Archbishop Desmond Tutu's childhood in South Africa. Hide Caption 16 of 16

The researchers found that after receiving the more encouraging letter about "high expectations," fewer black students had discipline issues the following year than those who received the other letter, and they were more likely to attend a four-year college. There were no significant associations found between the letter and behavior or college enrollment among the white students.

However, Cohen said the results of this small experiment should not be misconstrued to suggest that giving a nice note to a student will increase their chances of going to college.

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"That's not the message. The message should be that we can have more influence than we think, through timely acts that recognize and validate kids' potential," Cohen said.

"The note that we gave kids was one example of this, and it worked, in this place, in this time, in this school," he said. "Whether it would work in another school, I don't know. I think it would depend. It's not a magic bullet. The school where we used this note was one where the kids had the resources they needed to learn and to grow."

Tips to help teachers build trust

Teacher and student relationships are improved when teachers make an effort to better understand a student's life both in and outside of school, said Richard Milner, a professor of education and endowed chair of urban education at the University of Pittsburgh, who was not involved in the new study. He is author of the book " Rac(e)ing to Class: Confronting poverty and race in schools and classrooms ."

Based on research he has conducted in middle and high schools, Milner offered the following advice on how to build, cultivate and maintain trusting relationships with students: