Todd Graham is director of debate at Southern Illinois University. His teams have won national championships for three years, and he's been recognized twice as the national debate coach of the year. The opinions expressed in this commentary are solely those of the author.

(CNN) It's time to give the Republican candidates their grades for the final pre-New Hampshire primary debate Saturday evening. And by this point in the cycle, it's surprising that there's only one candidate who has mastered debate techniques sufficiently to get an A on my report card.

A

John Kasich: Kasich's delivery matched his content this time. His focus was on bringing everyone together. On immigration he reminded the audience that we need both to "lock the doors" by securing the border and to keep families of law abiding immigrants together. On leadership he reminded us that we are Americans first, political party loyalists second. On getting things done in Washington, he told of how he succeeded both as governor and as a congressman and argued that he'd be ready for the first hundred days. And he was the only one to successfully answer the question about bridging the divide between police and the community when he called his ideas a win-win solution. More importantly, Kasich's attitude and nonverbal communication was so much better this debate. Instead of incensed and interrupting, as he was in previous debates, he was happy, easy going, and likeable.

B's

Donald Trump: He still has trouble answering many questions, and his answer to the "how" question (asking to provide specifics) exemplified that. But here's what I like about Trump: He can handle the negativity from the audience. They booed him roundly at one point.

My debate team has lost debates because our opponents' teammates and friends stacked the audience against us. We handled the hostile audience poorly. Unless you've been there, you have no idea how difficult debating in front of a hostile crowd can be. So what did Trump do?

He called out the audience, of course. Trump gave us insider information such as, "Let me just tell you, we needed [debate] tickets. You can't get them. You know who has the tickets? I'm talking about to the television audience. Donors, special interests, the people that are putting up the money." ( The RNC later said that donors made up less than 10% of the audience.)

When they booed him even more, Trump transitioned perfectly to this, "The reason they're not loving me is because I don't want their money ... I'm going to do the right thing for the American public." I actually said, "sweet" when he utilized the backward-step-pivot-forward debating technique by turning a possible negative into a positive.

Ben Carson: He was humorous, as usual. But this time his answers were more coherent and less distorted than in previous debates. And he correctly called shenanigans on Cruz about Cruz's campaign telling Iowa voters that Carson had suspended his campaign. Cruz still He was humorous, as usual. But this time his answers were more coherent and less distorted than in previous debates. And he correctly called shenanigans on Cruz about Cruz's campaign telling Iowa voters that Carson had suspended his campaign. Cruz still incorrectly blamed CNN, but Carson called him out on it.

Jeb Bush: He'll never fix his slow, repetitive speaking style. And while he's getting better at arguing with Trump, as he did on eminent domain, they still aren't his best moments. However, Bush did what he does in most of the debates. He reminded us of his accomplishments as governor of Florida, emphasized national security issues, and played moderate to Trump or Cruz's extremism.

C

Chris Christie: He almost got a B for his role as "spoiler" by ruining Rubio's night. Unfortunately for Christie, he was a mostly one-trick pony. After time and time again telling us how much better governors were than senators, I began to think maybe he had little else to say, so following his original message, I turned my attention to a governor. Unfortunately for Christie, it was a different governor.

D

Ted Cruz: The night began badly for Cruz with Carson calling BS on Cruz's explanation of the Iowa controversy. And throughout the debate, Cruz failed to answer many of the questions asked of him. One example: How can he pass his agenda if he won't implement new executive orders (other than overturning Obama's) and he refuses to work with Congress? He never got around to actually answering it. Oh, and when he answers the questions, he's getting fact-checked as "wrong" The night began badly for Cruz with Carson calling BS on Cruz's explanation of the Iowa controversy. And throughout the debate, Cruz failed to answer many of the questions asked of him. One example: How can he pass his agenda if he won't implement new executive orders (other than overturning Obama's) and he refuses to work with Congress? He never got around to actually answering it. Oh, and when he answers the questions, he's getting fact-checked as "wrong" too often on issues, like on the number of immigrants deported by Clinton and Bush.

F

Marco Rubio: Say what you want about Chris Christie, but he clowned Marco Rubio. Four times, under different questions, Rubio clumsily pivoted to some odd speech about how Obama knows what he's doing and it's bad for our country. All four of these topics elicited the same answer from Rubio, "Obama knows what he's doing."

The worst part of it was when Christie railed that Rubio ignores the question and just presents a "memorized 25 second speech." Rubio's answer? "Obama knows what he's doing..." No kidding. He gave the same 25 second speech while Christie and America looked, pointed, and chuckled.

All I could think of when watching this exchange was that young Senator who couldn't handle the pressure of delivering the Republican response to the State of the Union and reached for his glass of water. Rubio appeared exactly like so many novice debaters I've judged who don't know how to handle a cross examination, so they simply repeat whatever they've memorized.