After a few seconds, you feel your clothes get looser. "What th-", you stop when you hear your voice getting higher. Looking at your hands you saw as your sleeves began to cover more and more of them, eventually you couldn't even see them.
Looking up you saw your now older drinking something herself. She also began to shrink down. When you finally stopped shrinking, you were practically swimming in your clothes, a few seconds later, your sister was down to her original age, and simply looked at you with a big smile on her face.
"What did yo-", you were cut off when Kelsey tackled you to the ground, sitting on your chest she just giggled. "What are you doing?"
"Playing.", Kelsy said with a big smile on her face. "Now that were the same age, we can wrestle and it can be fare."
"Wrestle?!? we've never wrestled.", you say confused.
"Lots of kids at school wrestle with their brothers I wanted to do it with you.", Kelsy said.
"Fine, i'll wrestle with you, I'll even let you win, just change me back.", you say, hoping she would take your word for it, and he could just back off when your back to your own age,
"You'll have to beat me first.", Kelsy said, then got off you and ran down the hall, "You'll have to find me."
Laying on the floor, you could not believe your current situation, not only had you been reduced to a nine year old, but your only way back to your age was to wrestle your little sistser. Looking at the potion set, you consider trying to make the potion yourself, but there was always a chance you would mess up and either make things worst or run out of ingredients. Now he could either take the chance or chase your sister and wrestle until she gives up.