UNION, Mo. (KSDK) -- At Central Elementary in Union, Mo., the best teachers may just be two students.
"They are both individually incredible," said first grade teacher Adrienne Koester.
First graders Vincent Butterfield and Zac Gossage are very good friends and often very silly.
"Why does the chicken cross the playground?" Vincent joked. "To get to the other slide!"
But recently there wasn't a lot to laugh about.
Last June, after feeling ill and tired for weeks, Zac was diagnosed with acute lymphoblastic leukemia, a fast-growing cancer of the white blood cells.
"As a parent, you want to make sure nothing bad ever happens to your child and when something does you want to be able to fix it," said Stacy Tooley, Zac's mom. "And I couldn't."
Still, while everybody around him took it hard, Zac took in stride. Despite frequent trips to the hospital, he almost never missed a day of school.
"Because I get to play with Vincent outside at recess," he said.
As for Vincent, he started asking questions and learning about cancer.
"It's when you're white blood cells and your red blood cells fight," he said.
Then he learned that Zac's treatments were expensive.
"We had been making these scarves and he just kind of said it would be cool if we could make a whole bunch of these and sell them," said Vincent's mom, Karen Butterfield.
He sold more than 20, earning a couple of hundred dollars.
"'You raised $200?,' we asked. 'And who did you give it to?' 'Zac!'" Vincent said.
Vincent also found out that Zac might lose his hair because of the chemotherapy treatments. So one day, he showed up to Mrs. Koester's first grade class wearing a stocking cap.
"And he said, 'Mrs. Koester I have a surprise for Zac.' And I said, 'Well, you do, yes I do.' And he pulls off his stocking cap and here I see that he shaved his head," Mrs. Koester said.
"I cut it off to make Zac feel like he's not the only one without any hair," said Vincent.
Zac continues to get treatments and continues to come to school every day. And Vincent, well he may be young, but he's teaching us the oldest lessons.
Reporter: "What is friendship?"
He thought for a moment and said, "A beautiful thing."
Clearly, wisdom doesn't always come with age.