Lesson Rationale: This lesson "Defining Cancer" is the first of five lessons within the course's first instructional unit (Unit 1: Cancer defined and Hallmarks of Cancer) which aims to introduce students to the morphological & physiological activities which distinguishes cancer cells from normal cells in the body. Prior to this unit, students experienced several days of engaging in the general inquiry process unspecific to cancer and have participated in a classroom activity which addresses the question "Who are the faces of cancer?". These lessons precede this lesson in the effort to develop scientific habits of mind in the classroom setting and to develop a sense of cancer's ubiquitous nature cross categorically. The idea is to aid in their curiosity to know more about this disease and how to pursue this information.
NGSS Standards Covered:
Conduct an investigation to provide evidence that living things are made of cells; either one cell or many different numbers and types of cells.
|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|
Lesson Preparation: The day before this lesson' implementation, it might be a good idea to have both a physical set of copies and a multimedia embedded (via prezi, powerpoint, etc.) copy of all the lesson's images, the evaluation strips cut and placed in an envelope for each group, and a presentation to facilitate the flow of the lesson to minimize potential instructional problems.
In this section of the lesson, students first individually and then collectively develop an initial or rough definition of cancer. They do so by following the sequence of instructional events:
a) Students are first prompted to define cancer based on their general experiences. The instructor leads by asking the entire class "What is cancer?" "That is, how do we define what cancer is based on what we know or think we know about it?". Give students an opportunity to mentally brainstorm and record their definitions in their notebooks/lab books prior to asking them to share their thoughts with the class.
b) The instructor then collects students' thoughts via verbal solicitation. More specifically, teachers should ask "What are your thoughts?" and then select students who both volunteer their definitions and those who don't and record their responses on the board. You should opt to collect at least 30% of the class's responses for a good representation of thought. Students should express their definitions leading with Cancer is...... and should be allowed to articulate their definitions comfortably. The idea here is to develop a collection of ideas as well as misconceptions from students to direct an instructional emphasis as you progress through the lesson.
c) The instructor then shares with the group that they will now examine formal definitions of cancer put forth by professional organizations to see how their listed definitions compare and contrast to formally accepted ones. Students should consequently then be presented with the cancer definition quotes on the board, screen or in the form of cut out strips and instructed to read them in designated groups of 4.
d) Now having been exposed to more structured definitions, students should be instructed to rethink, reconstruct, and further develop or modify their definition of cancer using commonalities of their original definitions and the formal definitions presented. They are not to rewrite any of the definitions presented, rather take the time use some of the common words of the definitions to enhance their rough definition. The teacher should circulate around the room and examine students work as they work through this part of the reconstruction process.
e) After definition modification, select students from each group should be called upon (voluntarily and involuntarily) to share with the class verbally how and why they restructured their definition. Assure students that change is good and necessary for progress to encourage for them to change and share their new definitions.
f) To transition to the next stage of the lesson, the instructor will ask students if they are completely satisfied with their definitions and if not what would be needed to authenticate their words.
In this section, students are given an opportunity to personally observe and record data on the differences between normal cells and cancerous cells. The idea here is to allow students to collect data that will contribute to the next step of refining their definitions. This time however, students will be able justify their added constructs with the data so that they understand how research centers and organizations develop the fine-tuned products that they were exposed to earlier in the lesson. The teacher transitions students into the this first lab experience by stating: "We've just stated that we require x, y and z to enhance our definitions of cancer. Let's begin by establishing and observing what normal versus cancerous means on a cellular level. Let's begin with some normal cells that you have, your cheek epithelial cells." At this point, students are then requested via class announcement set up a way to see and to record as their inner cheek cells and to follow the video procedure below:
After the video, students will be loosely facilitated through the process of collecting, staining and visualizing their "normal cells" under a microscope.
Next students are given an image and explained to that they will examine similarly treated cancerous cheek cells that they will use to compare & contrast their cheek cell stains to. They are then to record their observations (both drawings and words) of both cell types in their note or lab books under the heading:
"Data: Normal Cheek Cells compared to Cancerous Cheek Cells"
Next and in the effort to make certain that students are assessing and describing the cells' morphology correctly, a review video of animal eukaryotic cell structure entitled "Animals Cells Structure & Functions Animation Video for Kids" from youtube will be shown to the class. It is intended for a younger audience but provides a colorful and entertaining review of cellular structures for this purpose of the lesson. Students should be encouraged to label some of the structures seen in their images that are described in the video for a more informed definition revision later.
Post-video, the students are instructed to reshape their definitions by incorporating some of the morphological distinctions of cancer cells discovered in this segment of the lesson. The changes don't have to be elaborate. Just remind students that their definition is a work in progress and that they are going to use more observations to continuously modify their definition as is done in the scientific community.
Finally, a few definitions should be orally shared with the class by students. At least one example should be displayed on the board to show evolution of one's definition:
Student A's Preliminary Definition -> Student A's Revised Definition (Post Formal Definitions) -> Student A's Revised Definition (Post Cheek Cell Demonstration)!
In this section, students are given in pairs or presented with one unlabeled image of cells. The image contains a combination of normal stained cells and stained cancerous cells. Students should be verbally directed to switch definitions (notebooks or lab books) with a person outside of their designated groups, examine the cells on the image and identify at least five cancer cells based on the latest version of the student's definition of cancer only. Make certain that students understand that the definition is serving as a guideline for diagnostics at this point. Then ask the following questions after giving students at least five minutes to complete the aforementioned task:
a) Were you able to differentiate the cancer cells from the healthy cells in the person?
Pause and allow for students to verbally share responses.
b) Which part of the definition if any was particularly helpful in guiding your success of identifying these cells?
Pause and allow for students to verbally share responses.
c) Do you think that this definition is enough to accurately describe cancer? Encourage students to think back to the formal definitions before they address this question.
Pause and allow for students to verbally share responses.
Ask: Might there be more to cancer's story? Should we continue to advance our knowledge to shape our definition further? Let's explore.
In this section of the lesson, students further build on their observations and collect more data on what it means to be a cancerous on a cellular level. To extend their current, readings on both normal and cancer cells, students engage in a lab which allows for them to qualitatively visualize and assess the level of a specific growth receptor, HER2 on cancer cells versus normal cells. This section should advance in the following sequence of events:
A) Say to students "While we have been able to peek inside of cells which informs us of their nature, we can also see the outside using special tests. The outside of all cells have tiny little receptor which helps identify them & differentiate themselves from others, even if they are housed in the same body. For instance, liver cells have special receptors that marks them as hepatocytes or liver cells as opposed to cardiac muscle cells, etc." (Teacher, display simplified cell receptor image to students to emphasize location and specificity of receptors on the surface of the cell) Ask students "Do you think that cancer cells from the same body part have a different quality or quantity of receptors on them compared to their neighboring cells?" Have students hypothesize on this and record their hypothesis in their notebooks or lab books. Check around the room as students are writing to ascertain students' comprehension of the task. Inform students that we are going to test their hypothesis. We are going to test two blood samples one from a patient with cancer and one without. We are going to test each person's sample with an antibody or something that binds readily to the cell's receptors or antigens and clump or agglutinate if they are compatible. The level of clumping aids in qualifying the receptor count for each. In this case, the antibody is for the HER2 receptor (growth receptor) found on cells in general. Let's see if the cancer cell has it and if it has more or less than normal cells if so. (See HER2 testing attachment for directions)
B) Ask students verbally, "What do your results unveil to you about cancer cells' exterior anatomy or hallmarks as compared/contrast to your normal cells?" Is your hypothesis correct? Why or why not?
Pause and allow for students to respond between each question. Then, discuss the advantages and disadvantages of having similar receptors, but varied quantities on both cancer and normal cells as a class.
C) Finally and during the post lab and discussion stage, direct students to once again revise their last definition according to their observations from the results of the extension lab activity and the classroom discussion.
To wrap up the lesson, students in their groups of four will be given an envelope of strips with descriptive terms for both cancer and noncancerous cells. These terms are housed on the attached evaluation chart pdf. This chart will be cut and sorted into individual rectangles for students to reorganize in chosen schematic. The instructor will state to the class "We will now take the time to assess we know about cancer so far. I am going to hand an envelope to each group which contains 12 strips of descriptive terms. It is your challenge to figure out how they are to be organized. You and your team members will have 5 minutes to complete this task". Let students know when to begin and end the task by announcing start and stop. Then ask for a few student volunteers to explain their schemas to the class verbally and how it relates to what they have learned in the lesson today. Once, the final activity is completed, and all schema's are checked over by the teacher for accuracy, the students will be instructed to individually put a final revision on their definitions of cancer and submit their series of developed definitions for formal assessment.