This is a wonderful hot day activity or even for in the bath. I first saw the idea on pinterest here http://alittlelearningfortwo.blogspot.ca/2011/09/ice-eggs.html
So one day while the kids were busy playing outside I started gathering little toys and knick knacks from around the house. I also found some balloons from the last birthday party. B held the balloons open as i started filling them with nuts, marbles, small horses, screws, all sorts of random things. Some were filled with hot water which made the water freeze clear, some with cold water which made them freeze cloudy. Next I added a few drops of food colouring to some, finger paints to others and left some clear. I do not recommend the food colouring as it does stain. Using balloons made them egg shaped. They took the night to freeze and the next day we set them outside with some spoons for digging and a magnifying glass. Sun and Star loved them! They were like those discovery wands where you turn it and find all the little pics and stuff. Sun was occupied for a very long time slowly chipping away and finding every last treasure. Star liked the way the ice felt and how once it started to melt she could use her fingers to dig out the treasure. They held them up and looked at them from all angles. Discovery eggs were easy and successful, we will do them again, (without the food colouring), I think perhaps in the bathtub would be fun, and adding sparkles.. Ive also seen a pinterest post where someone made them round and put them outside in the winter as decorations that look like marbles, kinda cool but we prefer to play with them. Hope you enjoyed this post, please comment with your thoughts and come back soon!
Try using salt to help break down the ice, it works wonderful and leaves a discussion about science open. We even tried colouring our salt and pouring it on the ice eggs. Very neat.