Watch: Irish girl can't get her head around 'tonne of feathers or tonne of rocks' riddle
An Irish girl has been captured on camera having difficulty with the concept of whether a tonne of feathers or a tonne of rocks would be heavier.
Megan O' Neill's mother submitted the video to Independent.ie, writing that the clip shows "My daughter Megan trying to answer the dilemma!"
The hilarious clip shows poor Megan falling foul of the infamous riddle, "which weighs heavier, a ton of rocks or a ton of feathers?"
The answer, of course, is that both objects weigh the same - as both are a ton - but Megan doesn't quite understand this at first.
"That's like saying one feather or one rock... obviously rocks.. because they're much heavier!"
"One multiplied by a ton... is a lot!"
When her friend continues to push her, Megan says "shut up... I'm positive!"
Watch the video above.