Eggmosis - Teaching Selectively Permeable Membranes with Eggs

This post came about because I was trying to prove to my friend that I could remove the shell of a raw egg and still keep its contents in tact.  Because it takes a few days, I took pictures to send as proof and voila, not only to I have hard proof, but I have a neat little science demonstration to share!

Because of the inner membrane underneath the shell, an egg is a perfect tool when teaching students about selectively permeable membranes.  This demonstration takes seconds to set up and can be left out for a few days for students to observe.  Materials needed are: raw egg, vinegar, karo syrup.

Day 1: Take raw egg and cover with vinegar - the acetic acid will take about 24 hours to dissolve the shell which is made of calcium carbonate, giving off carbon dioxide bubbles as seen below. Sometimes more vinegar needs to be added if you really want all the white of the shell to disappear.

 Day 2: Rinse off egg carefully under water and show students the difference in size next to a raw egg.  Another thing to have handy is a scale if you want to have them follow the increase in mass.

Day 2 cont.: After students have made observations, a discussion can begin about osmosis and cells being placed in a hypotonic solution (solution where water content is higher than that of cell).  Next, have students predict what will happen to vinegar-soaked egg once it's placed in karo syrup overnight...

 The karo syrup is a hypertonic solution (solution where water content is lower than cell), therefore, the permeable membrane of the egg allows water to leave the cell and move into the syrup.    Here's a pic of all three eggs: vinegar-soaked, syrup-soaked and raw.  Easy and memorable!!!  Have fun!

3 Million Teachers Strong Sale

Teachers Pay Teachers is throwing a site-wide sale this Thursday and Friday (2/27-2/28) to celebrate the success of 3 million teachers collaborating and sharing on TpT!!  Use code TPT3 when shopping and pick up some of those products that have been sitting on your wish list!!

Interactive Notebook Pages - Part 1

I wanted to share with you some of my student interactives that I use for the student output side of the Physical Science Interactive Notebook.  Students REALLY enjoy the variation of activities and you'll love the creativity that students show in their work!  Check out what teachers have to say about using Interactive Notebooks in Physical Science:

"LOVE THIS! So helpful! My kids love the activities and I love how easy it is to prepare the activities. I feel like I don't need to go out and buy a bunch of supplies to do fun, interactive things!"

"I absolutely LOVE your units!  Since I started incorporating these my students have gone from not all that into it and doing whatever bare minimum they could get away with to my last test I had every student pass!!! You have truly made a difference!"

 The following example of a student interactive is one I made for teaching the Conservation of Energy.  In this activity students are asked to draw a scene (onto a "movie strip") that would illustrate the Law of Conservation of Energy.  They then place their "movie strip" behind the television cut-out and can slide it to show their example.

 Another interactive example is using this circle foldable to help with three-variable equations - in this case a work equation:

The final example I would like to share with you today is one I created to help explain how lightning forms during a storm.  With this lightning foldable, students cut it out then need to sequence the events of a lightning strike on each side.  Just thought it was a lot more fun then just writing down a paragraph!

You can find these interactives and more in The Complete Physical Science Interactive Notebook which covers all topics taught throughout the year!

I would love to feature some of your students notebooks on my blog if you ever want to share - I know you'll be so proud of their beautiful work!

Bubble Plasma Membrane Demo

Well, my New Year's Resolution was to start adding posts to this blog to share my ideas...it's now February so I better get my act together :)
Good old Punxsuatawney Phil gave us a few more weeks of winter, so better make the most of it and have a little fun indoors.
A great way to do this is to play with bubbles and bubbles (I think) are THE perfect tool when trying to teach the properties of the plasma membrane.

Using two straws, make a frame to use as your bubble maker:

Once the frame is complete, mix up some bubble solution in a cookie sheet or tray and start your Plasma Membrane demonstrations such as...flexible boundaries

...or semi-permeable membranes...

...or really get a reaction from the students when you demonstrate embedded proteins by taking a piece of looped thread, placing it on the bubble solution and popping the inner circle to represent a protein channel. Also, move the thread loop around to help explain to students that the cell membrane can "repair" itself when the proteins move around the membrane.

Students can also complete this activity in groups - I give students directions on how to complete each activity, then I have them summarize the comparison between the behavior of the soap bubble to that of a plasma membrane in their Life Science Interactive Notebooks.  You can find this activity and more in the Life Science Interactive Notebook - Cells: Structure and Function chapter of my Interactive Notebook series.