The Egg Activity
Author: Brian P. Kraatz
Overview: This activity covers topics related to the process of science. It deals with the steps of science and focuses primarily on the first step, observation. Specifically, students will study chicken eggs to formulate observations, descriptions, and hypothesis.
Note: Depending on the level of the students you may or may not want to bring the term of Hypothesis into the discussion. Although important for them to learn, it may confound the overall purpose of the lesson by introducing terminology. And personally, I still get tripped up on what an actual hypothesis should be.
Time: 1 hour
The instructor should outline each of the three steps of science and give an example that the students can use as comparison (i.e. a thought experiment that demonstrates the scientific process). One example may be drawing out a picture on the board showing a field of flowers with a large wall on one side of the field. Flowers that would receive more sunlight could be drawn taller. This cartoon would be their observations. Use this model to discuss why some flowers would be taller than others. Have them develop a statement about this, probably something like “flowers would grow taller if they receive more sunlight.” Next have them discuss a potential experiment to test this statement, which would probably involve a green house and various levels of lighting.
Now begin the egg exercise. The students are first asked to describe the exterior of an egg without looking at the egg. Most will likely say things such as smooth, white, ovoid — this is an excellent opportunity to open this up to group discussion to see how all the students described the egg (as with every other descriptive step in this lesson). Each student should then be given an egg and some type of dish that they will eventually crack the egg into. If you have too many students, feel free to put them in groups and have them share the eggs. The students should then have a chance to revise their descriptions. It should become clear to the students that the eggshell is a much more complex structure that has many pits along with some slight discolorations. Next the students should be asked what the inside of the egg should look like if it were cracked open. The students will probably describe and egg yolk and an egg white. After they have exhausted their list of descriptors for the inside of the egg allow the students to crack open each of their eggs and add anything they want to the description. The instructor should go through the structure of the egg at this time (which also could be relevant in future discussions about the evolution of amniotes). The students should begin to see many structures that they had previously not thought about.
The next portion will deal with hypothesizing or developing statements about their observations. After the students have thoroughly observed the their eggs, they should be asked to come up with a hypothesis or statement — based on their observations — of what will happen to an egg if it were thrown into the air and allowed to hit the floor. Their hypothesis will likely be that the egg will crack open, splattering egg white and yolk all over. This brings the students to the final step of science — testing. Ask the students how this hypothesis or statement should be tested. Explain to them that you will throw the egg at the floor to test this hypothesis. It is important for the instructor to have previously prepared a hard-boiled egg that the students are not aware is hard-boiled. The instructor will then throw the hard-boiled egg at the floor and wait for the students’ reactions.
Following this should be a discussion about why the hypothesis or statement was not correct. The main points should involve how each step of the scientific process is important and how the students’ hypothesis may have been different had they been able to observe the egg that was thrown to the ground. Their observations would have been different, and in turn their hypothesis or statement would have been different. Ask them how they may have known that the egg was hard-boiled (have some extra hard-boiled eggs that they could observe), and how this may have altered their hypothesis.