Noah was seven years old and lived in a lovely house with his two sisters. Nadia, the eldest at eleven, was sweet and responsible, always ready to help her little brother. Nina, the youngest at four, was a whirlwind of energy who wreaked havoc wherever she went.

That Wednesday afternoon, Noah sat at the kitchen table, staring desperately at his math notebook. The multiplication problems were giving him a headache. Nadia, who was doing her own homework next to him, noticed his troubled expression.

"Do you need help, Noah?" she asked kindly, leaning towards him.

"Yes... I don't understand this multiplication. It's too difficult!" he sighed.

Nadia smiled patiently. "Don't worry, I'll explain. Look, when you multiply 7 by 3, it's like having 7 candies three times over."

While Nadia calmly explained math to Noah, Nina was playing in the living room. Well, "playing" wasn't exactly the right word. She had decided to transform the sofa into a castle by piling up all the cushions, then she emptied the box of crayons onto the white rug to create a "giant rainbow."

"Nina! What are you doing?" their mother shouted from the laundry room.

The little girl with the blonde pigtails ran to hide behind Noah. "I'm playing!" she replied innocently.

Noah rolled his eyes. This was Nina's third mischief today, and it was only three o'clock. In the morning, she had drawn on her bedroom walls with lipstick, then she had given Moustache, the family cat, a bath, which he hadn't appreciated at all.

"Come on, concentrate, Noah," Nadia encouraged him, gently tapping her notebook. "You're almost there! Try this one: 8 times 4."

Noah thought intently, counting on his fingers. "Thirty-two?"

"Bravo! You see, you can do it!" exclaimed Nadia, affectionately ruffling her hair.

Their moment of intimacy was interrupted by a loud "BOOM!" coming from the bathroom. Noah and Nadia exchanged a worried look. Nina had disappeared again.

They rushed to the bathroom and found Nina standing on a stool, the entire tube of toothpaste squeezed into the sink. "I'm making snow!" she announced proudly, covered in toothpaste from head to toe.

"Nina! Mom is going to be very angry!" said Noah, shaking his head.

Nadia, ever patient, took a washcloth and began to clean her little sister. "Nina, you have to stop being naughty. You know it's not right."

But Nina just laughed, splashing foam everywhere. Noah sighed again. Sometimes, having a four-year-old little sister was really exhausting.

Later that evening, after their mother had scolded Nina and cleaned up all the mess, the family gathered in the living room. Noah had finished all his homework thanks to Nadia's invaluable help.

"Thank you for helping me today, Nadia," said Noah, giving her a hug.

"You're welcome, little brother. It's normal, we're a team!" she replied, smiling.

Nina, sitting quietly for once, looked at them with her big eyes. "Can I be part of the team too?" she asked in a small voice.

Noah and Nadia looked at each other and burst out laughing. "Of course, Nina," said Noah. "But you have to promise to stop the nonsense!"

"I promise!" said Nina, crossing her armsfingers behind his back.

The three children knew full well that Nina would start her mischief again the very next day, but that was family life, too. And despite all the chaos, Noah knew he was lucky to have his two sisters: Nadia the protector and Nina the whirlwind.