Summer of Science 2012 – Rubber Eggs

First I want to do a little homeschool mom whining.  At the beginning of the year I spent several hours, over the course of several days, mapping out our curriculum calendar.  During Christmas break I made adjustments, namely switching to year-round homeschooling, to better fit with family activities, work schedules, and my desire to spend a portion of the day outdoors and on field trips.  So how…oh, how…did I end up out of work?  More than that, what am I going to do to fill those mandatory hours for the rest of the year?

The answer my friends…science experiments.



Looking at this stack of books, that it seems like I should’ve thought of this a long time ago.  These pages contain enough science experiments to get me through this year and well into the next!

So I’m pleased to bring you a preview of my newest series: A Summer of Science!  Beginning in June (that’s just a few days from now), every Tuesday and Thursday, I’ll be sharing a science experiment geared towards keeping our little brains thinking throughout the summer months!  Don’t worry, most of them will be quick and easy with supplies you already have at home.

Now on to the preview…Rubber Eggs!


I used Janice VanCleave’s Biology for Every Kid as a reference for this experiment, whose purpose is “to demonstrate the semi-permeability of a cell membrane.” 

Materials needed:

• An egg or two (The book called for raw eggs but we used hard-boiled ones.)
• A jar with a lid that the egg can easily fit inside
• Vinegar  (Um, it’d probably be better to use clear but I used a salad vinegar that I didn’t like…waste not want not.)

Directions:


After you’ve hard-boiled the eggs, being careful NOT to crack the shells, simply put them into the jar with the vinegar.  I tried to cover the eggs with it.  Close the lid and let it sit for at least a few days. 



We kept ours on the countertop so that the kids could watch what was happening.  And when they ask, what’s with all the bubbles,  it’s your time to step in, think to yourself “What would Mister Wizard say,” and explain…

The shell is made of a substance called limestone.  When the vinegar comes into contact with it a chemical reaction occurs and carbon dioxide, a gas, is produced, creating the bubbles.



The shell will eventually dissolve  and turn into a sludge on top of the vinegar.



The membrane around the egg doesn’t dissolve, but since it is semi-permeable it absorbs a bit of the water in the vinegar and give the egg its spongy, rubbery texture. 




Note:  My little ones were 6 & 5 when we did this experiment, but if you have scholars a bit older I would recommend following the book’s instruction more directly.  Measure the egg before, during, and afterwards, record it all, and then explore osmosis and its effect in this experiment.