Have fun with a friend trying this Blast Lab Egg Salt and Spoon Race.

What to do:

1. Place 2 of the chairs side by side facing forwards. Place one bowl on each chair and empty the salt into the bowls. This is the starting point of the course.
2. Some distance from the first 2 chairs (you can choose) place the remaining 2 chairs side by side. Place the other 2 bowls on these chairs and fill them with water. This is the finishing point of the course.
3. Between the 2 sets of chairs create an obstacle course. (Perhaps set up cones that you have to weave in and out of.)
4. Once your course is ready, place one egg in each of the bowls of water at the finishing point. The eggs should sink.
5. You and your friend should go to the starting line with a tablespoon each.
6. The aim of the game is to load your spoon with salt from your first bowl, go through the obstacle course (hopefully without spilling much salt) and then tip the salt left on your spoon into your bowl of water at the end of the course.
7. The more salt you add, the more likely the egg is to float. You can also use the spoon to stir the water to help the salt to dissolve.
8. If your first spoonful of salt doesn't make the egg float, return to the start of the course, load up your spoon with salt and do the course all over again. Don't forget to stir your water after you've added the salt.
9. The first person to get their egg to float wins the game.
10. If at first you find this too easy, you can always make your water bowl bigger, your salt carrying spoon smaller, or the course more difficult. If, instead, you find it too difficult then swap your salt spoon for a small beaker.

For an object to float on a liquid, the liquid must be more dense than the whole of the object and the air contained within it. In normal water, its particles are spread out so it's not that dense. This means, at first the water is less dense than the eggs, which is why they sink. But with each spoonful of salt you add, the water increases in density. When enough salt has been added, the salt water will eventually become more dense than the object, and so it can now float.