TEMPE, Ariz. -- The daily grind of an NFL season might appear tough. Early-morning meetings, lifting sessions and daily practices can be grueling. The physical punishment can take its toll. Aches linger. Pains come and go.
Barnes and his wife, Talia, homeschool their four children in Houston, Texas. Every day during the week, Khalif and Talia teach, tutor, parent and tend to 7-year-old Zoe, 5-year-old Zane, 4-year-old Zara and 2-year-old Zion, juggling curriculums and classes so each child can stay on top of his or her academics while getting the one-on-one attention afforded by homeschooling.
"It's so much one-on-one time," Khalif told ESPN. "They're eager to take their tests, and it's just us and them. That's it. It's school. No time to play around with your friends. They're 100 percent. It's like us going to camp. It's that kind of setting."
The kids also have a social life through other children in their neighborhood, so they're getting to experience all aspects of being in grade school without actually being in school -- for now, at least.
Khalif has been impressed with the school system in Houston, where his family lives full time, and he plans to enroll his children in schools there at some point in the future.
When? He doesn't know. Until that decision is made, he'll trade in the title by which most people know him -- NFL offensive lineman -- for the ones he has come to embrace: math teacher, P.E. teacher, art teacher, chef and dad.
It's a role he carried with him to Arizona in December.
Khalif, yet again considering retirement, had yet to play in 2017 before the Cardinals signed him on Dec. 12 as a replacement for the injured Jared Veldheer. In three games in Arizona, he played eight offensive snaps, including some at tight end. While Khalif was playing in Arizona, Talia finished up the semester with their children in Houston and then visited him in Arizona for the start of their winter break and the rest of the Cardinals’ season. Once the season was over on New Year’s Day, the Barnes’ family eventually went back to Houston to begin the second semester.”
During the spring of 2016, Khalif considered his football fate.
He was a free agent, and while teams were convening for organized team activities and minicamp, Khalif was in Jacksonville, Florida, with his family, working out, staying in shape, hoping for a call and contemplating retirement. The plan was for the Barnes family to move to Houston as soon as their house was built.
Then the phone rang. The New Orleans Saints asked Khalif to come to town the last week of the preseason for a tryout. He went. They liked him. They signed him. That started a run of the Saints signing and cutting Khalif five times from Aug. 30, 2016, to Sept. 1, 2017, partly because of his weight and partly to make room for other players.
While their father was traveling back-and-forth from Jacksonville to New Orleans, Khalif's school-aged children went to Providence School of Jacksonville, a private Christian school where their grandmother was head of the church, Khalif said.
While Khalif chased his football dream, he didn't want to take his children out of school. The situation was too unknown. He wanted them settled. They were going to stay in school in Jacksonville for the time being. But with a move to Houston awaiting them in January 2017, change was also inevitable.
That's when Talia made the decision to homeschool all four kids.
"I'm calling her from New Orleans saying, 'Hey, you sure you want to do this?'" Khalif said.
Talia admitted to him that it wasn't easy, but she preferred it over moving the kids from school to school.
After the move to Houston, Talia continued to homeschool the children for the second semester of the 2016-17 school year. However, she had help.
Khalif started serving as the family chef. He made breakfast for his kids and then, over time, became their physical education, math and art teacher.
The longer Khalif helped Talia, the more his role grew.
After Talia worked with a child one-on-one upstairs, he or she would head to Khalif downstairs. Which child he was working with would dictate the activity. When 4-year-old Zara came to work with Khalif, he helped her with arts and crafts.
"I was kind of artsy," he said.
Khalif helped his oldest daughter, 7-year-old Zoe, with math. Then Khalif and Talia would trade, and each would work with the other two kids on different subjects.
"It's a little teamwork thing where you would do this section, you would do this section," Khalif said. "I sat back, and I looked at her, and she was doing all this work, and I was working out and seeing if I wanted to play football or not. And she was just doing this, and she got used to it. ... She said she wanted to do it until they were in fifth grade. I said, 'There's no way you're going to keep this pace and want to do this until they're in fifth grade.'"
This year, Zoe is in second grade, and Zane and Zara are in pre-K.
"They're all reading well," Khalif said. "They're all writing well. They're all understanding comprehension well. It's just amazing.
"At first I was like, 'There's no way I'm going to be able to do it.' And when you get into a rhythm of it, you get a lesson plan down, and you start remembering stuff that you were doing as a kid. I think the one thing that's good about it is that, as opposed to them being in a class with other students and they get a certain amount of attention, they get 100 percent of the attention with their teacher -- or us -- right then and there."
Together, Khalif and Talia have found a daily routine. Their goal is to make the children's day as similar as possible to a day at a traditional school. Just the venue is different.
They try to wake the kids at the same time every day and start school between 8 a.m. and 8:30 a.m. But as much as Khalif and Talia want to keep homeschool the same, there are some benefits to not having a morning drive.
"The good thing about homeschool, you can kind of start school whenever you want, and you don't have to rush people out," he said. "But we still want to start school at the same time during the day time to stay on the schedule and get done at the same time to stay on the regular program."
When the Barnes children start school, they do the Pledge of Allegiance, read a Bible verse and tell a Bible story.
A typical day goes like this: First up is Zara. She starts with coloring and works on her ABCs with Talia upstairs. Then she goes downstairs to Khalif to either do more coloring or work on crafts. When Zara goes downstairs, Zoe begins working with Talia upstairs on a math course. After a while, Zoe goes downstairs, and Zane does math with Talia upstairs.
When Zane goes downstairs for a break, Zoe goes back up to work on linguistics. After a while, all the kids end up downstairs for a Bible show on YouTube.
Then comes lunch, and Khalif sometimes puts "Tom and Jerry" on for his three older kids to watch during a post-lunch break while Zion, the 2-year-old, takes a nap upstairs. After the break, Zoe, Zane and Zara continue to work on math or arts and crafts.
"Pretty much how it goes from Monday to Friday," Khalif said.
The more Khalif helped Talia, the more he saw similarities between learning and football.
"Just the constant drilling of it," he said. "It's like what we do: repetition. Anything that you're doing, you're going to get familiar with and you're going learn better, as opposed to you being in an atmosphere with multiple kids, and sometimes you don't get the one-on-one time that you might want or need on certain subjects."
The kids get weekly tests that Khalif and Talia grade, and they also have tests that measure their progress in various subjects.
Khalif and Talia use a Christian-based curriculum they discovered at a homeschooling conference in Houston. They bought the curriculum, which provides classwork and lessons for an entire school year.
Thus far, his children have been excelling, Khalif said.
"They all pass it with A's," he said. "My oldest daughter, she took off with it. She's a wiz."
Watching his children in an educational atmosphere on a daily basis has also given Khalif the type of insight into who they are as kids and students that he wouldn't have if they went to a traditional school every day.
He has noticed that his older son, 5-year-old Zane, likes to "play around a little" and has a short attention span. The benefits of homeschooling have been evident, Khalif said. Zara, the 4-year-old, has shown signs of being smarter than her two older siblings, Khalif said, because "she just sits back and listens" to her brother and sister. Even 2-year-old Zion has already started to talk and has begun working on his ABCs, Khalif said.
But Zion still needs constant care and attention. With three siblings who can do work on their own for the most part, Zion makes focusing on the other children difficult, Khalif said.
"I have to keep him distracted and busy until it's time for him to take a nap, and then that's when we can get everything else done," he said.
Although the Barnes children have been succeeding and making progress, their parents are still first-time teachers.
During their first year homeschooling their children -- the 2016-17 school year -- Khalif and Talia noticed that Zane wasn't picking up what they were teaching. They were starting to get frustrated. They finally realized that they were teaching him the lesson plan that he was supposed to be learning this year.
"We felt kind of bad about that," Khalif said. "He's going to retake the course, and it should be flying colors for him.
"He just got extra prepared, that's all."
When Khalif first started teaching his children back in late 2016, his mind would travel elsewhere.
He thought about football, about how he still wanted to play, about being cut by the Saints. During the offseason of 2016, which he now calls his "half-retirement," he battled that inevitable feeling every NFL player deals with: What was he going to do next?
"That midlife crisis thing that a lot of players go through," he said.
But after he returned home to Jacksonville in November after getting cut by the Saints for the last time in the 2016 regular season, he was able to put football away and start thinking about what mattered to him: watching his kids grow up.
Part of that meant teaching them.
"At first, I was like, 'Oh, man, c'mon,'" Khalif said. "Then I got into it, and to see them get something, it's the rewarding thing about it. We've been working on the letter S or counting by 10s to 50, and every time they get to 10, 20, 30, 40, when they get to 50, they can't say the word 50. So they say 'seven.' And when they get it, when you've been working on something for about a week, I guess that's how our coaches feel about us."