After a while, Alex eventually decided to go back to his homework, but Katherine didn't let him go.
He was forced to do it while sitting on her lap, which he didn't mind, besides the little distraction inside his head.
Page 19 was another similar question, which Alex was able to complete after thirty minutes of solving it.
With only one page yet, Alex took a short water break as he turned over to see what part the other two girls were at.
To his surprise, the other two had just started page 17, and there was still a long way to go.
Shifting his attention back to the paper at hand, Alex completed it after another half an hour of work.
"Whew, there goes the math homework." Alex lets out a sigh of relief as he puts the stack of homework back into his backpack.
"Good job, Alex. Muah! You are the best son I ever had!" Katherine declared as she kissed him on the cheek.
"As if she has another son..." Sophia murmured as Katherine blushed a little in embarrassment.
"Mom, can I go back to my room to take a break?" Alex suddenly asked.
"Sure. Go for it... You two, get back to work. You are not eating lunch today until you finish your math homework."
Both girls let out a sigh as Alex ran out of Katherine's warm embrace into the hallway.
---
"Fuck, that was way too close..."
Alex's heart was beating faster than ever as he quickly closed his bedroom door before sitting down on the bed.
He could feel a tent that had formed below. It had been painfully up since Katherine hugged him.
Her sudden kiss on the cheek almost pushed him to the limit as he could feel his pants already leaking a little.
Despite his attempts to take a deep breath and open the window to calm himself down, nothing worked.
It just couldn't go away, as his brain kept flashing Katherine's warm body surrounding him every second.
Unable to resist the urge, he took off his pants and underwear before grabbing a piece of tissue.
Gently, he began stroking it a little, giving him a sense of relief temporarily.
But it was also causing him to want even more, which he did by rewarding himself with another stroke with his hand.
As he continued to stroke his erect cock with his left hand, he started moving his other hand further down.
The sensation almost made him reach orgasm on the spot from just gently rubbing onto the little bump underneath his testicle.
Remembering what Mom had taught him, Alex began to slowly insert a finger inside the entrance after feeling a little empty inside.
"Hm!"
Alex couldn't help but moan out an extremely feminine voice as the sensation was now doubled.
Just as he was about to climax, he suddenly could hear the door being unlocked.
Within seconds, he immediately lay down flat on the bed before grabbing his pants and pulling the blanket back up.
"Alex, you okay? What was that sound?"
After changing it, Alex fixed his clothes before heading back to the living room.
---
"Welcome back. You awake from your nap?"
Katherine stood behind the two girls, teaching them how to solve one of the problems on page 17.
"Yeah..."
After sitting down, Alex turned his attention to the second stack of homework.
As he read the first page, he was surprised to find it something similar to a periodic table, albeit with tons of gaps in between.
"Mom, what is this homework?" Alex asked curiously as he handed the paper to her.
"Oh, it's alchemy. Why did your teacher assign this so early... Alex, can you wait for a bit?
I need to finish teaching Sophia this question first. Then, I'll teach all three of you guys about this."
"Okay."
Alex waited as he watched Katherine patiently teach the same stuff that he already knew about.
"Brother, can you help me on this?" Mary asked, seeing Katherine was too busy helping Sophia.
"Sure."
As Alex looked at Mary's work, she was still working on the first problem on page 17.
"Okay, I'm going to start from the beginning to make sure you understand it fully."
An hour later...
Sophia and Mary were sitting right before Alex, working on the last page of the math homework after Katherine made him explain to both of them.
Meanwhile, Katherine had just come back from the kitchen, carrying a tray full of food for the three of them.
"Nice, you two are almost finished. You all can take a break after this if you want."
After putting the food on the table, Katherine watched as the two girls put their pencils down as they finished the math homework.
Even though there was still one more stack of homework, both of the girl's faces were full of smiles.
It was almost as if they had overcome their biggest life challenge, happily grabbing the food before eating it.
"I'm definitely taking a break after this. Writing so much today hurts my arms," Sophia complained, as she could feel her brain drained of energy.
"Mom, can you take us around the city?" Mary requested as she took a bite of the food.
"I'm Sorry, Mommy has work later, okay? But I can ask Luqing later to bring you guys outside."
Mary looked a little disappointed, but she was still happy with the result.
"Mom, I want to finish all of the homework first. I thought you promised me you were going to explain this after they were done."
Alex argued as he began putting a piece of the food into his mouth.
"Well, Alex, I want to help you. But it seems like both of your sisters want a break."