Embedded Files
Lesson Overview
Lesson Overview
Guiding question: What are cells and tissues?
Time Estimate: 2.5 hour
Purpose: In this lesson, students will delve into cells, tissues, and levels of organization. This space has the potential for instructors to tailor it to their needs and cover standards. Since this lesson precedes the exploration of cultured meat, it is crucial to address the key scientific content knowledge about cells, tissues, and levels of organization.
Overview: Before delving into the study of cells, students will explore the global demand for meat using graphs. As the demand for meat is expected to increase over time, alternative protein sources are being introduced to the public. One of the most well-known alternatives, plant-based meat, will help connect students' experiences to the issue more closely. However, global predictions for meat consumption indicate that among alternative proteins, cultured meat is expected to dominate in the future. Therefore, students will learn about cultured meat. However, before delving into this new biotechnology, students should have a foundational understanding of cells, tissues, and levels of organization.
Design Principles:
Learning experience contextualized in the issue
Practice oriented
Background Knowledge: All necessary background knowledge will come from this lesson.
Common Misconceptions:
Students may think that all cells are identical in shape and size. Emphasize the diversity in cell shapes and sizes, highlighting examples like nerve, muscle, and red blood cells.
Students might believe that tissues comprise only one type of cell. But, tissues are often composed of different types of cells working together to perform specific functions.
Students may believe that all cells within an organism have the same functions. It is important to discuss how cells differentiate and specialize to perform specific tasks within an organism.
Safety: NA
Unit Connections:
📂 Materials
📂 Materials
Teacher
Teacher slides 4.1 What are cells and tissues
Student
Student material: 4.1 Introduction to Cells
Student material: 4.1 Plant and Animal Cells Lab
Student material: 4.1 Reading Plant & Animal Cells
Student material: 4.1 Levels of Organization Sort
Student worksheet answer
Student material: 4.1 (answer) Introduction to Cells
Student material: 4.1 (answer) Plant and Animal Cells Lab
Instructional Sequence
Instructional Sequence
Materials: Teacher slides 4.1 What are cells and tissues
Global demand for meat (Slides 2-5)
The red bar illustrates the world's meat demand in 2005. Ask students if they expect an increase in demand by 2050 and why or why not.
Encourage students to describe the graph, guiding them to discuss the rising demand for meat. The blue bar indicates that global meat demand will increase in 2050. We need to increase food production to feed the growing population.
However, increasing meat production should not be our option for the future. As discussed in lesson 3.1, meat production negatively impacts the environment. Let students ponder: If we acknowledge that the demand for all types of meat is increasing, how does this demand affect our planet? It's crucial to understand that as we strive to meet the needs of a growing population, we must explore ways to provide healthy, protein-rich, and sustainable food both in the near and distant future.
🗣️ Discourse opportunity:
Class discussion
Alternative protein sources (Slides 6-7)
The instructor will introduce five alternative protein sources to address the future demand. Students will be asked to share their experiences with one of the alternatives, plant-based meat, the most well-known meat substitute.
Several potential solutions exist for our current and future protein needs; some are still developing, while others are already available in our supermarkets. Ask students whether they have heard about these alternatives.
The instructor doesn't need to explain each protein source in detail, but it's important to inform students that various methods of substituting meats have been developed and are still evolving.
Global meat consumption in 2050 (Slide 8):
The graph illustrates predictions regarding the future trend in meat consumption. Notably, vegan meat, like plant-based meat, is expected to decrease slightly, while conventional meat is projected to drop significantly. Conversely, cultured meat is anticipated to experience a dramatic increase.
🗣️ Discourse opportunity:
Class discussion
📒 Instructional Support
Probing questions
Have you ever seen plant-based meat?
Have you ever tried plant-based meat?
How did it taste?
What kind of information can you gather from this graph?
Cultured meat (Slides 9-10)
The graph presented in slide 7 introduces a new term—cultured meat. In biology, 'cultured' signifies something grown in an artificial medium. Students can grasp two crucial words: ' grown' and 'artificial.'
Cultured meat refers to the artificial growth of meat. In the next slide, students are asked, 'How do we grow meat in a lab?' To grow meat, we need to understand what constitutes meat, and that is muscle meat. Therefore, to grow meat, we need to grow muscle cells.
🗣️ Discourse opportunity:
Class discussion
📒 Instructional Support
Note
Meat is not solely composed of muscle cells; it coexists with fat cells and other cells. However, the typical composition is predominantly muscle cells.
Introduction to cells (Slides 11-13)
To comprehend cultured meat production, students first need to grasp fundamental scientific concepts, starting with cells. The cell, the smallest unit with the basic properties of life, will be explored through a worksheet where students can learn about its basic mechanisms.
Students will complete a worksheet while watching a video.
Video: Introduction to Cells: The Grand Cell Tour
📕 Worksheet
Student material: 4.1 Introduction to Cells
🗣️ Discourse opportunity:
Class discussion
⏰ Recommendations for timing
The video has a duration of 9:26.
💡 NC standards
7.L.1 Understand the processes, structures and functions of living organisms that enable them to survive, reproduce and carry out the basic functions of life.
Plant & animal cells (Slide 14-18)
First, students will observe the differences between animal and plant cells using a microscope. Using a microscope for a hands-on activity would be beneficial if it is available in school. While observing animal and plant cells, students will complete the worksheet.
If there isn't a microscope available for students, please refer to the second worksheet, which contains images captured exactly as seen through the microscope.
Afterward, they will read about the general ideas of plant and animal cells and review their observations from the microscope.
📒 Instructional Support
✍️ Assessment Opportunity
What to look for?
Use worksheets to assess understanding of the standards.
This is the space for instructors to evaluate the content knowledge related to the NC standards.
Fat & muscle cells (Slides 19-22)
Cells exist in a variety of shapes and sizes within one creature. Address to students that we will compare human cells performing different functions, such as muscle and fat.
The instructions are described in slides 19 and 20, so please have students follow the steps. Even though there is no worksheet for this, encourage students to think that cells exist in various shapes and sizes. This is important because students will be introduced to stem cells in the next lesson, explaining how cultured meat is made.
🗣️ Discourse opportunity:
Group discussion
Levels of organization (Slides 23-28)
After exploring cells, students will progress to the tissue level. Cells can be likened to building blocks; to create a figure of meat we can eat, these blocks need to be assembled. When specific cells come together, they form a structure called tissue. Muscle tissue, for example, is akin to a team of muscle cells connected in strands.
Lastly, students will watch a video about biological levels. Then they will sort levels of organization into three different parts of humans and animals. This activity will help students understand the hierarchical relationships between these levels.
Slide 21 is an answer for the sorting activity.
Video: Biological Levels in Biology: The World Tour
📕 Worksheet
Student material: 4.1 Levels of Organization Sort
🗣️ Discourse opportunity:
Class discussion
⏰ Recommendations for timing
The video has a duration of 5:10.
✍️ Assessment Opportunity
What to look for?
A sorting activity can serve as an assessment tool for understanding content knowledge.
Information for Planning & Teaching
Information for Planning & Teaching
Background Knowledge
Cell Theory
In 1858, Rudolf Virchow, using microscopes much more advanced than Hooke’s first microscope, developed the hypothesis that cells only come from other cells. For instance, single-celled organisms like bacteria divide in half (after growing some) to produce new bacteria. Similarly, your body generates new cells by dividing the cells you already have. In all cases, cells only come from cells that have existed before. This idea led to the development of one of the most important theories in biology: the cell theory.
The cell theory states that:
1. All organisms are composed of cells.
2. Cells are alive and the basic living units of organization in all organisms.
3. All cells come from other cells.
As with other scientific theories, many hundreds, if not thousands, of experiments support the cell theory. Since the cell theory was developed, evidence has yet to be identified to contradict it.
Levels of Organization
While cells serve as the basic units of an organism, groups of cells can collaborate to perform specific functions. These specialized cells are so named because they have distinct roles. Specialized cells can then be organized into tissues. For instance, your liver cells are organized into liver tissue. The liver tissue, in turn, contributes to the formation of an organ—the liver itself. Organs are created when two or more specialized tissues work together to perform a particular function. All organs, ranging from your heart to your liver, comprise an organized tissue group.
These organs, in turn, are integral parts of a more extensive system known as organ systems. For example, your brain collaborates with your spinal cord and other nerves to constitute the nervous system. This organ system must be organized in conjunction with other systems, such as the circulatory and digestive systems. Organ systems collaborate to form the entire organism. Indeed, living things exhibit numerous levels of organization.
Lesson Timing
Student Ideas & Experiences
Incorporating microscopes into the middle school science curriculum enriches the learning experience, promotes scientific inquiry, and lays the foundation for a deeper understanding of biological concepts. Microscopes provide a hands-on learning experience that engages students actively in exploring the microscopic world. This tactile approach helps students better understand and recall scientific concepts. Using microscopes helps students develop important scientific skills such as observation, critical thinking, and attention to detail. These skills are essential for scientific inquiry and investigation.
Science Practices
Teaching Cases
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