Even kindergartners can enjoy this well-known activity. Just divide the children into groups, and tell each group that they will get exactly three eggs to experiment with. Their goal is to come up with an idea of what they could use to make the egg fall without breaking. Encourage students to choose materials they have in the classroom or can bring from home the next day. On the following day, let students try out their ideas and see which ones work. (You may want to cover the floor with a tarp in order to reduce mess when the eggs drop.)
Put a raw egg into a bowl of vinegar and instruct your kindergarten students to observe the shell change over the next couple of days. The vinegar dissolves the eggshell and makes the egg bounce when you drop it. As a class, you can make a Venn diagram on the board and use it to compare and contrast the two states of the egg. Make sure not to let students drop the soft egg from a height of more than a few inches or the egg might burst.
This craft project is more unique than most of the typical egg crafts out there. To make an egg mosaic, crush plenty of egg shells and put a pile of them in each of several little bowls. When you add a bit of food coloring to each bowl and mix well, the crushed egg shells will become dyed that color. Let the shells dry well before using them for a mosaic. Then let kindergartners use the dyed shells to fill in any outline, such as those in a coloring book.
Kindergartners often enjoy drawing faces, and this activities taps into that interest. Give each child a hard boiled egg (to reduce mess), and let them make their own egg people. If you'd like, you can turn this into a listening activity, where you call out the facial feature and give children time to add that feature to their egg faces. For example, you might say, "Now add two eyes to your egg face," and give children time to draw two eyes on their eggs.