Snowball, Snowball!

It's snowing!
Brother and sister Kian and Dina love snow.
And so, the frosty downpour of twinkling snowflakes has them
bursting with excitement.
"Bet I can roll a bigger snowball than you!" Kian says.
"Bet you can't!" Dina replies, sticking out her tongue
The contest is on.
The biggest snowball wins.
And boy, do those snowballs get big!
But who wins . . . and why?
Well, there's only one way to find out. Open the book and read!