The self-heating rice was getting louder and louder. Yue Zhishi turned his head and mouthed to Jiang Yufan, "Why is this thing making noise??"

Jiang Yufan shook his head frantically, gesturing and mouthing back, "I don't know either..."

Hu Xuan from the front seat turned around, raising a hand to make the sign of the cross over her chest with an expression of silent mourning.

But Song Yu seemed to be cut off from the world, showing no reaction. He had even already drawn half a mind map on the blackboard. Behind him, the entire class held back their laughter, performing a brilliant pantomime. The only accompaniment was the sound of the self-heating rice, comparable to an ever-intensifying symphony in the Golden Hall.

Not only that, the experience was also 4D. Hot white steam, along with the aroma of shredded pork with garlic sauce, wafted out of Yue Zhishi's drawer.

He had only wanted to eat a meal sneakily, but now, great, the entire class, including the supervising Song Yu, knew he was cooking.

Yue Zhishi completely gave up. A scene had already formed in his mind: he would be reprimanded, ordered out of the classroom, and then be left squatting in the hallway, eating his meal miserably.

He felt that he was now a very experienced person, one who could go on Zhihu and vividly give an anonymous answer to the question, "What is it like to experience social death?"

Finally, ten long minutes passed. Song Yu turned around expressionlessly and placed the half-used piece of chalk on the lectern. "This is what I'm going to talk about next."

The sound from the self-heating rice began to resemble a deflating balloon, growing weaker and weaker, just like Yue Zhishi's head, which was now drooping onto his desk.

"First part, find your weakest link. You all understand the bucket effect." As Song Yu continued to speak, he stepped down from the lectern as expected.

Below the lectern, row by row, students hurriedly put away their phones. The ones in the very front turned to look at Yue Zhishi, ready to watch a show.

The person rumored to bully his younger brother was supervising the class and, as luck would have it, had caught said brother sneakily eating. It would be completely unjustifiable if he didn't give him a harsh lesson.

"Systematically organizing your mistakes is an effective method. Making mistakes isn't scary; everyone makes them. What's scary is that many mistakes are repeated over and over, ultimately leading to lost points. So, what you should do is reduce the frequency of making the same mistake."

As he spoke, he had already walked to Yue Zhishi's side, his long, slender hand resting on Yue Zhishi's desk, seemingly unintentionally.

His pace was steady and his logic smooth as he went from the topic of organizing mistakes to techniques for scoring on math multiple-choice questions, like the graphical method, the substitution method, and so on. But Yue Zhishi, acting like an ostrich, couldn't hear anything except the thumping of his own heart.

It was as if Song Yu was deliberately torturing him, standing right beside him and lecturing, not moving anywhere else.

"...That's it for the multiple-choice section. Now, use the problems you have on hand to practice the techniques I just mentioned. You have ten minutes." After speaking, Song Yu finally lowered his head and looked at Yue Zhishi, who had been playing dead the whole time. His bent knuckles tapped lightly on the desk.

Only then did Yue Zhishi pitifully raise his head, wearing an 'I really know I was wrong' expression, and obediently took out the self-heating rice box hidden in his drawer.

Song Yu raised an eyebrow, his voice very low. "Does it smell good?"

Hearing this, a few nearby students couldn't hold back their laughter.

"It's okay," Yue Zhishi answered very honestly, then added in a small voice, "It's a little fragrant."

Jiang Yufan was a loyal friend. Seeing that Song Yu seemed intent on making things difficult, he immediately explained, "Senior, I'm the one who bought this. I bought the wrong one, my bad, my bad. I can write a self-criticism."

Seeing him try to take the blame, Yue Zhishi immediately spoke up, "No, I was the one who wanted to eat it."

Zhang Chen, who loved a good drama and didn't mind stirring up trouble, said, "Senior, I can prove it. Yue Zhishi was the one eating. They were sneakily planning this for a long time. They just wanted to eat self-heating rice during evening self-study."

Jiang Yufan was furious. "Do you have any right to talk? As if you haven't eaten takeout during evening self-study. Besides, he wasn't even planning to eat in the classroom."

As the two started to argue, Song Yu's gaze swept over the laughing students. Everyone seemed to be filled with anticipation for his disciplinary action. Finally, he spoke, his face impassive.

"Taking this opportunity, let me explain to everyone the principle behind self-heating rice."

Zhang Chen's face was full of disbelief. This was a complete departure from the name-taking, punishment-standing, and tattling combo he had expected.

Ignoring the quiet chattering of the students around him, Song Yu picked up the rice box from the desk. "Look here."

"The bottom layer of a self-heating rice box contains a heating pack, which has chemical agents like quicklime, sodium carbonate, and an aluminum-magnesium mixture. Quicklime, which is calcium oxide, reacts with water to produce calcium hydroxide, releasing a large amount of heat at the same time. Sodium carbonate often plays an auxiliary role, and aluminum-magnesium powder can also release heat through an oxidation reaction. So when we add water, the heating pack activates and automatically heats the food."

He lowered his head, his gaze meeting Yue Zhishi's astonished eyes, and continued, "However, this kind of self-heating instant food also carries a risk of explosion, and the food isn't very fresh. I don't recommend you all eat it often."

With that, Song Yu put down the rice box and turned to point at the blackboard. "I've already written the relevant reaction equations in the bottom-right corner of the board. Anyone who's interested can take a look."

Yue Zhishi looked at the equations on the blackboard. So he had known what was happening all along, and had calmly written them up there.

At first, everyone just thought it was funny and wanted to watch the show unfold. They never expected the social death incident to suddenly morph into a chemistry lesson, and they were a bit stunned. The amazing thing was, they had learned some of these reactions before but had never connected them to real life. To see the connection now felt strangely magical.

"Connecting this to the recent example," Song Yu said, leaning against Yue Zhishi's desk, "none of you should ever forget that the reaction of calcium oxide with water is exothermic."

Everyone laughed in unison. But Zhang Chen was clearly not satisfied. He raised his hand, a cheeky grin on his face. "Senior, so why did it make a noise? It was hilarious."

This was a clear attempt to redirect everyone's attention back to the sizzling sound the self-heating rice had made.

Leaning against the desk, Song Yu didn't answer directly. Instead, he looked at the other students. "You all have done chemistry experiments, right? Can anyone tell me about any experiments you've done that made a distinct sound?"

A girl spoke softly, "Sodium and water..."

Song Yu nodded at her in affirmation. "That's a classic example. Many chemical reactions produce sound," he said, pointedly glancing at Zhang Chen, "It's nothing to make a fuss about."

Zhang Chen's expression faltered, as he could clearly feel the trace of mockery in the other's cold tone.

"Aside from the reaction itself, the exothermic process also generates a large amount of water vapor, which can make noise as it rushes out. This process involves many reactions, like those in a galvanic cell, that you haven't learned about yet."

Song Yu lowered his head, glancing at him. "I believe... if classmate Yue Zhishi had understood the principles behind this from the start, he wouldn't have chosen to heat self-heating rice in a quiet environment."

Classmate Yue Zhishi.

This form of address sounded strange to Yue Zhishi, and yet, for some reason, it sparked a trace of pleasure.

Although Song Yu still wore a cold expression, it wasn't one of blame. Even though every sentence was ostensibly about popularizing chemistry knowledge, anyone could hear the hidden intention of letting Yue Zhishi off the hook.

'Now I can add a real-time update to the bottom of my anonymous answer,' Yue Zhishi thought. '"I'm alive again!" No, he could even un-anonymize it.'

As he was spacing out, a large palm landed on his head and gave his soft, fluffy hair a brief, light ruffle. He didn't have time to react; he only felt the hand leave his head, leaving a single sentence behind.

"It'll get cold if you don't eat soon."

This sudden head-pat surprised the surrounding students.

The rumor that the brothers had a bad relationship fell apart on its own in the face of Song Yu's extremely rare, intimate gesture.

Without even raising his head, Yue Zhishi said, "I'll go eat outside."

He said this, then picked up the rice box and walked out, his movements a little stiff.

The washroom was to the right of the stairwell, next to the restrooms. Seeing that no one was there, Yue Zhishi slipped inside. The convenience food tasted very ordinary; the rice was hard, and the dish was a little too salty.

He chewed in a daze. After swallowing, as if possessed, he raised a hand to touch the top of his own head, then lowered it and took another large bite.

He was so hungry he didn't even feel hungry anymore, and after everything that had just happened, Yue Zhishi didn't have much of an appetite. Remembering that Jiang Yufan had wanted to try some, he didn't leave after he finished eating. But poor Jiang Yufan had been through too much and forgotten all about it; Yue Zhishi waited for five minutes, but he never came.

Song Yu was still in the classroom, so Yue Zhishi didn't want to dawdle. He cleaned up and returned. When he got to the doorway, Song Yu was at the lectern explaining the English review plan. Yue Zhishi stood at the entrance, quietly called out, "Report," and waited to enter.

Hearing his voice, Song Yu nodded at him, then nonchalantly continued with his lecture.

Yue Zhishi quietly returned to his seat and listened along with the other students. Throughout the whole period, Song Yu, who hadn't brought any notes, had taken only ten minutes to structure the mind map's outline. Then, with clear logic, he led everyone through it, his ease and proficiency surpassing even that of many teachers.

"Time is limited, so that's all for now." Song Yu stood to the side and glanced at his watch. The first evening self-study session was about to end.

"Yue Zhishi."

Hearing his name called, Yue Zhishi froze for a moment, then quickly looked up at his brother.

Song Yu jutted his chin towards the blackboard. "Erase the board."

Yue Zhishi immediately nodded obediently. "Mhm," he said, starting to get up.

Growing up, the thing Yue Zhishi feared most was Song Yu ignoring him, especially after he'd done something wrong. But if Song Yu scolded him or gave him some small, punishment-like task, it meant he wasn't actually angry.

When Song Yu was truly angry, he would be silent.

They knew each other that well.

"Don't erase it," a girl who was taking notes looked up. She hadn't paid much attention during the explanation and was now rushing to copy the board. "I'm not done copying." Others chimed in, leaving Yue Zhishi in a dilemma.

Song Yu glanced over coolly. "Since your phones can be used for chatting, they can probably take pictures too."

Everyone was rendered speechless by this remark, especially those who had just been gossiping and laughing about the situation in a group chat.

The bell rang, and Song Yu left the classroom. Yue Zhishi went to erase the board as he was told. Being a loyal friend, Jiang Yufan grabbed another eraser to help him. "Was the rice good?"

"It was okay." Yue Zhishi looked at him. "I waited for you for five minutes, but you didn't show up."

"Oh, so you were waiting for me? No wonder you took so long. I completely forgot." Jiang Yufan rolled up his sleeves. "That idiot Zhang Chen was dissing you, saying you must have been too embarrassed to come back. It pissed me off so much. He's just taking out his frustrations on other people because he can't get what he wants."

Yue Zhishi energetically erased the blackboard, not particularly concerned about what was said in his absence. "He'll just get his kicks talking for a day or two. If the person I liked fell for someone else, I'm sure I wouldn't be happy either." The hand holding the eraser suddenly paused, and Yue Zhishi's gaze fell upon the few lines of equations in the corner.

This was the last, unfinished part of the cleaning task Song Yu had given him.

"Do you have your phone on you?" he asked, turning to Jiang Yufan, who was dusting off his hands.

"Yeah, what's up?" Jiang Yufan pulled it out and handed it to him. "You're only thinking of taking a picture now? Everything's gone."

Yue Zhishi said nothing, simply using the phone to take a picture of the equations in the bottom-right corner.

"Thanks. Send this picture to me."