Egg-Speriment

SCIENCE – 6TH Grade: The Egg-speriment Introduction: Our bodies are made up of cells that are responsible for every job our body does. But for our cells to perform all these jobs properly, they need to bring in certain particles from outside the cell. One way for particles to enter the cell and help it do its job is to simply pass through the cell membrane. All living cells are surrounded by a membrane which separates the stuff inside the cell (water, nucleus, etc.) from the stuff outside the cell (water, other cells, nutrients, etc.) This membrane determines what can enter the cell and what should stay outside. One way that it prevents certain particles from entering is by having holes only large enough to allow small particles to enter. It is therefore called a semi-permeable membrane. An analogy could be made to a basketball net. Only certain size balls will get through. That is, a tennis ball will go through the hoop, a basketball will go through the hoop, but a big beach ball will not. The same holds true with cell membranes. Many particles, such as sugars and salts that are dissolved in the water surrounding the cell try to enter the cell, but they are too big and therefore cannot pass through the membrane. DEMONSTRATION NOTES: Demonstration #1: Materials: 1/2 cup salt 1/2 cup dry beans jar with lid (quart or liter) colander large bowl Describe the procedure followed for this demonstration – Describe what you observed during this demonstration – What conclusion can you draw from this demonstration? Demonstration #2: Materials: ( 1 ) beaker or clear cup 1/2 cup of water 3-4 drops of food coloring Describe the procedure followed for this demonstration – Describe what you observed during this demonstration – What conclusion can you draw from this demonstration? EGG-SPERIMENT: At last to the main part of the experiment -- here an egg will be the model for a cell. The “problem” or purpose in this experiment will be to explore and discover the processes of osmosis and diffusion. As you work through this experiment, look for information that will help you to understand how osmosis and diffusion work in a cell. First, the shell must be removed to expose the cell membrane. Vinegar takes care of this job very easily because it is an acid that reacts with the calcium in the shell to remove the shell. Once the shell is removed, the concepts of diffusion and osmosis can be illustrated. The egg will be transferred from the beaker with vinegar to a beaker containing various other solutions. You and your team will make observations on the condition of your egg, on a daily basis throughout this experiment. Objectives: To understand one way that materials enter a cell To understand the function of the cell membrane To understand the principles of diffusion and osmosis To record careful and detailed observations of a scientific experiment Vocabulary (you will be expected to understand and be able to use this vocabulary by the time you complete this experiment): cell cell membrane semipermeable membrane concentration diffusion osmosis circumference Materials: for each group of students: (3) 250 ml beakers or big clear cups (1) egg (be careful handling the egg!) 12" piece of string ruler, paper and pencil to record observations Procedure: Carefully weigh and measure the egg that your teacher will give you. Use a triple balance scale to weigh the egg. Use a piece of string and a ruler to measure the circumference of the egg in both directions (lengthwise and around the “middle”). Record your measurements in the table below. Place egg into one of the beakers. (Be careful -- do not drop the egg in.) Fill beaker with enough vinegar to cover the egg. Record observations immediately. What do you notice? Continue to record observations over the next three days. Be sure to note how the egg feels when you touch it each day. Don't squeeze too hard – it will be fragile! Throughout the remainder of this experiment, your egg will be immersed in a variety of solutions including corn syrup, plain tap water, water with food coloring, and salt water. Make a hypothesis about what you believe will happen to your egg as you work with it in this experiment. Follow the directions given by your teacher for how to complete the rest of this experiment. Required Outcomes: Directions: Write your responses to the following on notebook paper (you may type it if you choose). All responses must be written in complete sentences where appropriate. Use your best handwriting, and pay attention to spelling and appropriate grammar. § Describe what you understand about the problem that was explored through this experiment. § Describe the procedures that you followed throughout this experiment. § List all of the materials used in this experiment. § Define the vocabulary given above. § Answer the following questions to turn in:

Why was the shell removed first? How did the egg change from the beginning of the experiment to the middle to the end? Explain why using the vocabulary above. How did the egg change while it was in the syrup? Explain why this change occurred? What do you think would happen if the egg was placed in orange juice instead of corn syrup? Why? What caused the changes that you observed when the egg was placed into water? What did you observe when the egg was placed into salt water? Explain why this occurred. If you could place the egg in another liquid of your choice, what would you choose? Predict the outcome for the egg in the solution you would choose for it. § Extension: In order to make his shows more entertaining to the public, Mr. Barnum of Barnum and Bailey Circus, decided to collect whales from the ocean and display them for his audience. He collected the whales and kept them in large uncovered tanks until showtime. Unfortunately, it rained the opening day of his show. The salt water in the tanks, which held the whales, was diluted by the rain that fell that day. This change in the amount of salt in the water compared to the amount of water, caused the death of the whales. Unwilling to admit to his audience that the whales were dead, he told them that that day's rain would cause the cancellation of the show. Not to fear, he would give everyone a check that would allow them to see the next whale show. He would give them a rain check. Mr. Barnum is credited with coining the phrase "rain check". What does the death of Mr. Barnum's whales have to do with the experiment you have just completed on the subject of osmosis? To complete this experiment, you must attach your notes and observations to the written work required above. Lab Report Evaluation Rubric --

0, 5, 10 -- Clear and Appropriate HEADING, TITLE, PROBLEM, and HYPOTHESIS. 0, 5, 10 -- All MATERIALS listed and a summary of PROCEDURE. 0, 10, 30, 50 -- Appropriate presentation of DATA and observations including graph(s), chart(s), drawing(s), etc. Accuracy of data. 0, 10, 20, 30, 40, 50 -- Clear and concise CONCLUSIONS. Conclusion addresses problem and states knowledge gained. Answers to all QUESTIONS. 0, 5, 10 -- Overall- NEATNESS, GRAMMAR, adheres to FORMAT, etc.