1. To engage my students to start to think about cellular structure I show them an interactive demo, by Learn Genetics, that allows students to observe cell size and scale. This demo does a great job in demonstrating the size and scale of cells by using comparisons to objects students are familiar with (coffee bean, grain of rice, grain of salt). (SL.7.5 - Integrate multimedia and visual displays into presentations to clarify information, strengthen claims and evidence, and add interest.)
Most critically, it communicates the idea that as small as cells are there are even smaller objects in the world (i.e. organelles such as mitochondria and lysosomes). A common student misconception is the belief that organelles are examples of cells rather than components of cells. One way of addressing this misconception is by allowing students to observe objects that are smaller than cells, facilitating the connection that organelles are tiny structures inside cells.
2. I follow the above demo by having students create annotated drawings of their vision of the inside of cells.
Annotated drawings encourage students to access their prior knowledge and visually represent their thinking. The act of drawing to explain a concept or phenomenon encourages sense making and awareness of one's own ideas. Students are challenged to think about how to visually represent and explain an idea with minimal use of words. That means the words chosen must be precise. Annotated drawings can be used at the beginning of a learning cycle/unit to engage students in a topic with which they have some familiarity.
The prompt that I give students at the beginning of the lesson is:
Based on what you just observed (Cell Size and Scale Demo) draw what you believe the inside of cell looks like. Label and briefly describe any parts of the cell that you include in your drawing.
It's very important that you emphasize to students that you are more interested in their ideas than the right answer or the artistic quality of their drawings.
In this section students begin working on Cell in the City. This activity will require 2 class meetings to complete.
This activity enforces what students have learned in earlier activities by building a cell city model (SP2 - Developing and Using Models/MS-LS1-2. Develop and use a model to describe the function of a cell as a whole and ways parts of cells contribute to the function.) by creating analogies between cell organelles and parts of a city.
Teacher Note: Depending on level of class it might be a good idea to read organelle cards as a class and point out the "clues" that will help students match the organelle with the analogous city person/structure.
Smooth and Rough Endoplasmic Reticulum
Function: The rough endoplasmic reticulum takes proteins from the ribosomes attached to it and finishes manufacturing them. The smooth endoplasmic reticulum manufactures and stores chemicals that the cell can use.
Match in City: Manufacturing Plants
Students read cK-12 Organelles. The text introduces students to organelles and their functions. This website includes two optional practice activities, where students can delve more deeply into the topic.
After reading the text, students are given the Word Analogy activity. In this activity students are asked to create word analogies using the organelles covered both in their reading and during the Adaptive Curriculum activity.
The organelles chosen for this activity are:
2. cell membrane
To evaluate student learning, I have students create a new annotated drawing. The purpose of this is to encourage reflection.
1. After students have finished their second annotated drawing they go back and revisit their first drawing from the beginning of the lesson.
2. Students are instructed to compare and contrast their two drawings and describe the learning experiences during the lesson that helped them gain a better understanding of cellular structure. (second drawing should have accurate labeling of organelles including a brief explanation of their function).
As a possible extension activity students may visit the following site where students can further explore and learn "Everything you ever wanted to learn about cells." Besides watching the video students can can complete the Think, Dig Deeper, and Discuss section of lesson.