Ice Eggs.

Ice eggs are an extremely simple activity, although they do require a bit of forward planning.  The idea is that you put an object (or two) in a balloon, fill with a little water and then freeze them.  When they are frozen, you cut the balloon off and you have an egg made of ice with a toy in it.  The challenge is for the children to get the toy out.

The lego men ready to go in their balloons.

Lego men safely in the balloons - it was a bit of a squeeze but I managed it!

Filled with water ready for freezing.  I meant to turn them after an hour to see if I could
get the men in the middle of the  egg, but what with one thing and another, I forgot.

Ice eggs ready to go!

The Feral One contemplates hers.

The Eldest and The Boy decide that smashing them on the floor is the fastest way to get into them.

The Eldest uses her teeth to get the last of the ice off.

In other learning objectives, we had a bit of a discussion about the type of animal that lays eggs and we wondered what might have laid these.  Variations on the ice egg theme include making larger eggs/cubes filled with lots of small objects (as opposed to just one or two).  They can then use "tools" to get these out and the activity lasts longer.  This could also lead to discussions about melting/freezing and/or the water cycle, but in the mayhem of the moment, I'm afraid this extension somewhat passed me by...