The Teenager - Mum have you seen my sunglasses?
Me - No. Where did you have them last?
The Teenager - I had them on when I cut the grass and I left them on your desk.
Me - Well I'll have a look but I haven't seen them.
Fast forward a week ...................
Me - Have you found those sunglasses yet?
The Teenager - No I've looked everywhere and can't find them.
Me - Have you checked that pig sty you call a room?
The Teenager - Yes I've looked but I can't see them. They're definitely not there.
Me - Well keep looking.
Fast forward another week ............
The Teenager - Mum!! You know my glasses?
Me - Yessss????
The Teenager - Well I've found them.
They were behind the monitor on my desk and I just never saw them!
A classic case of "I'm looking but I'm not seeing".