All science

Me (to my daughter): ‘Noëmi, what are you doing?’

She (14): ‘Measuring my weight.’
Me: ‘Ok, but shouldn’t you put those things down first from your hands?’
She: ‘No, because I measure myself every day and I know myself that I always carry the laptop/ gsm/ charger wherever I go, so I must have had them in my hand yesterday, too, when I checked my weight. And so if I measured myself without these things now, I would get inaccurate results..’
Ok. 
If it is scientifically underpinned then it’s all fine.