STRENGTH OF EGG SHELLS
TOPIC: How Strong are egg shells?
GRADE: 1-2 TIME: 45 minutes
CONCEPT: The testing of egg shells for structural strengths.
RATIONALE: This experiment will allow the students to understand how a given structure, such as the egg shell, is stronger than other structural shapes. In this way the students can learn under what circumstances a given shape may also come weak thus allowing them to understand how many beautiful architectural structures can exist without visible means of support.
OBJECTIVE: The students will be able to discuss and describe verbally as well as in writing why the structural shape of an egg shell makes it stronger or weaker depending on how it is cut.
PREREQUISITE SKILLS AND UNDERSTANDINGS:
- 1. Knowledge of what strong and weak means.
- 2. Knowledge that egg shells do break if the egg is dropped.
- 3. Understanding of what an experiment is.
VOCABULARY: Dome, Long Axis, Short Axis, Triangle, Square
MATERIALS: Cut two dozen eggs in half along the short axis and two dozen along the long axis. Save only those eggs shells that do not have large chips along the edge as they will cause weaknesses in the shells and cause faulty results. One pare of super fine fingernail scissors or if available a Dremel hand tool with a fine cutting blade on it. Numerous books of approximately the same size for load tests. Eight paper triangles, two in each of the color fo the table assignments.Science Experiment Journals. (Based on a classroom size of 20 students)
INTRODUCTION: Today we are going to see how strong our egg shells are. I have taken the egg shells and cut them in half along the long and short axis of the eggs shell.(Discussion; Who can tell me what the long axis and short axis is on the egg shell?) We are going to see which way the egg shell is stronger then talk about why you think one shape of egg shell is stronger than the other before we perform the experiment. We will be working in groups so (indicate the first child) please count off by 4's. Thank you for being so cooperative. When I give you the instructions, the 1's will be at the Yellow table, 2's at the red table, 3's at the green table and 4's at the blue table. Do you all remember your numbers? Now quietly and quickly walk to your tables please.
- 1. Have each table pick a person to report the findings for their group.
- 2. Have two of the students pick up several books from the classroom book shelf.
- 3. Have 1 student from each group pick up 3 egg shells of each type and two colored paper triangles.
- 4. Have students take out their science experiment journals and write down in their journals the group prediction as to which type of egg shell will be stronger.
- 5. Have the students write out a hypothesis and heading for the procedure, materials, results and conclusion.
- 6. Have the students place their colored triangles onto their desks.
- 7. Have the students carefully place the three like egg shells onto the points of their triangles.
- 8. Have the students test one set of egg shells at a time by carefully placing one book at a time onto the egg shells. When the weight of the books breaks the shells they are to record the number of books it took to break the shells. Have them repeat the process with the other triangularly placed eggshells.
CLOSURE: I'm going to write down on the board each tables findings. When I call on your table I want your reporter to give me the number of books it took to break the egg shells cut on the long axis and how many books were needed for the short axis.(Discussion) It appears by the results given by each table shows that the short axis or dome shaped egg shells were stronger. Can anyone tell me why they think this shape is stronger? (Discussion) Those are wonderful reasons, now can anyone find a picture in the room that shows a building with a dome shaped roof (Florence Cathedral). Lets go back and open your journals. We are going to see if your group predictions were correct. (Discussion) With a show os hands and no talking please show me if your predictions were correct.I now want you to complete the scientific entries in your journals and write your own conclusions as to WHY your results are correct or incorrect according to your initial prediction.
EVALUATION:The students will be evaluated on their ability to discuss the experiment and their outcomes as well as the completion of their science experiment journals.
SELF-EVALUATION:I will be able to evaluate my lesson through the class discussion and what the students have written. Furthermore, I will know where changes need to be made through these class discussions and the individual group work. .