April Investigation  3rd and 4th graders

Solve this riddle

I’m tall when I’m young and I’m short when I’m old. What am I?

LEASE LEAVE YOUR ANSWER AS A COMMENT AND MAKE SURE THAT YOU ALSO WRITE YOUR NAME AND YOUR CLASS NAME. THE COMMENTS WILL BE PUBLISHED AT THE END OF THE MONTH AND THEN WE'LL ALSO TELL YOU WHO ARE THE WINNERS. 

 PLEASE DO NOT GOOGLE THE ANSWERS...