Mathemavision
Have a guess first
Why are manhole covers round?
Stand over one on the footpath and have a guess. Then watch the reason get drawn on it. No manhole cover nearby? Use the photo.
Made for a kid about 7 to 12, with you beside them. The camera picture stays on your phone and isn't saved.
Stand over the lid with the phone pointing straight down. Change the ring's size so it sits on the lid's edge, then hold still and tap.
The camera didn't open, so here's a photo instead.
Why do you reckon it's round?
Have a guess out loud before you tap.
Clue: if you dropped a round lid and a square lid, which one could fall down its own hole?
A circle is the same width whichever way you turn it. So even tipped on its side, the lid's still too wide to fall down its own hole.
A square lid is wider corner to corner than side to side. Tip it the wrong way and it slides straight in.
Next time you step over one, you'll probably think of this.
Another one
Is your shadow longer at lunchtime or after school?
Guess first. Then look at your shadow now, and check it again at the other time, later today or tomorrow. Never look straight at the sun.
Show me why
When the sun's high, it shines down steep and your shadow's short. Later on the sun's lower, so the light comes in from the side and your shadow stretches out.
Thanks for trying it
How did it go?
If you're the parent, I'd love 2 minutes on what your kid guessed and said. A "meh" helps as much as a "wow".
Tell me how it went