Conduct an investigation to provide evidence that living things are made of cells; either one cell or many different numbers and types of cells

Standards Alignment

• MS-LS1-1 primary
  Conduct an investigation to provide evidence that living things are made of cells; either one cell or many different numbers and types of cells.

Lesson Overview

In this Grade 7 science lesson, students will conduct an investigation to gather and analyze evidence demonstrating that all living things are made of cells. They will explore the differences between living and non-living things, understand that living organisms may be unicellular or multicellular with varied cell types, and develop scientific explanations based on their observations. This lesson aligns with NGSS standard MS-LS1-1 and supports students in building foundational knowledge about cell biology through hands-on inquiry and evidence-based reasoning.

Learning Objectives

• Conduct an investigation to gather evidence that living things are made of cells.
• Distinguish between living and non-living things based on cellular structure.
• Explain that living organisms may be composed of one cell or many different types and numbers of cells.
• Use observations and evidence to support scientific explanations about the cellular nature of life.

Success Criteria

• Students can identify and describe cells as the basic units of life.
• Students can differentiate living things from non-living things based on cellular evidence.
• Students can explain that some organisms have one cell while others have many and varied cells.
• Students can communicate their investigation findings clearly using evidence.

Prerequisite Knowledge

Students should understand the basic characteristics of living things and non-living things and have experience making careful observations and recording data during investigations.

Key Vocabulary

• cell
• unicellular
• multicellular
• living
• non-living
• microscope
• observation
• investigation
• evidence

Materials and Resources

• microscopes or magnifying lenses
• prepared slides of plant and animal cells
• samples of unicellular organisms (e.g., pond water)
• samples of multicellular organisms (e.g., leaf, onion skin)
• non-living samples (e.g., salt crystals, plastic)
• observation journals or worksheets
• drawing materials

Teacher Preparation

• Prepare microscope slides of plant and animal cells in advance.
• Gather samples of unicellular organisms from pond water or provide prepared slides.
• Collect samples of non-living materials for comparison.
• Prepare observation journals or worksheets for students to record data.
• Review microscope use and safety procedures.

Detailed Lesson Notes

Understanding Cells as the Basic Units of Life

Cells are the smallest units that can carry out all the processes necessary for life. All living things, whether a single-celled organism like bacteria or a complex multicellular organism like a human, are made of cells. Cells can be very different in size, shape, and function, but they share common characteristics that define life. Recognizing cells as the fundamental building blocks of life helps distinguish living organisms from non-living things, which do not have cellular structures.

Unicellular vs. Multicellular Organisms

Some living organisms consist of only one cell; these are called unicellular organisms. Examples include many bacteria and some protists found in pond water. Other organisms are multicellular, made up of many cells that may be specialized for different functions, such as plant leaves or animal tissues. Understanding this distinction helps students appreciate the diversity of life and the complexity of cellular organization.

Conducting Investigations to Provide Evidence

Scientific investigations involve making careful observations, collecting data, and analyzing evidence to support explanations. Using microscopes or magnifying lenses, students can observe cells in prepared slides or live samples. They can compare these observations to non-living samples to identify characteristics unique to living cells. Recording detailed observations and drawings helps students gather evidence to support the claim that living things are made of cells.

Using Microscopes and Making Observations

Microscopes allow students to see cells that are too small to observe with the naked eye. Proper use includes focusing carefully, adjusting light, and handling equipment safely. Students should note cell shapes, sizes, and structures such as cell walls or membranes when visible. Observing differences between plant and animal cells, or between unicellular organisms and multicellular tissues, deepens understanding of cellular diversity.

Common Misconceptions and Clarifications

A common misconception is that all living things must be multicellular; students should understand unicellular life forms exist. Another is confusing non-living things that look complex (like crystals) with living organisms; emphasizing cellular structure and function clarifies this. Students may also think cells are visible without magnification; explaining scale and the need for microscopes addresses this. Encouraging questions and evidence-based reasoning helps correct misunderstandings.

Worked Examples

Classroom Activity

Students make detailed observations and drawings of what they see under the microscope and record differences between living and non-living samples.

Guided Practice

Independent Practice

1. Foundational: What is a cell?
2. Developing: How can you tell if something is living or non-living by looking at it under a microscope?
3. Application: Describe the difference between unicellular and multicellular organisms and give an example of each.
4. Analysis: Explain how observing cells in different organisms helps us understand the diversity of life.
5. Challenge: Design a simple investigation to provide evidence that living things are made of cells, including what you would observe and how you would record your evidence.

Independent Practice Teacher Answer Key

1. 1. A cell is the smallest unit of life that can carry out all the processes necessary for living things.
2. 2. Living things have cells visible under a microscope, while non-living things do not have cells.
3. 3. Unicellular organisms are made of one cell, like bacteria or some pond organisms. Multicellular organisms have many cells with different types, like plants and animals.
4. 4. Observing cells shows that some organisms are single-celled while others have many specialized cells, which helps us understand how life varies in complexity and function.
5. 5. Use a microscope to observe samples of pond water and plant leaves. Record detailed drawings and notes of cells seen in living samples and compare to non-living samples. Use observations to explain that living things are made of cells.

Guiding Questions

• What evidence shows that living things are made of cells?
• How do unicellular and multicellular organisms differ?
• Why do non-living things not have cells?
• How can microscopes help us learn about cells?

Common Misconceptions

• All living things are multicellular; some are unicellular.
• Non-living things can have cells like living things do.
• Cells can be seen without a microscope.
• Cells are all the same in every organism.

Differentiation

Assessment

• Observe student participation during microscope investigations and discussions.
• Review student observation journals for accuracy and detail.
• Ask students to explain their evidence orally or in writing during class.
• List two pieces of evidence that show living things are made of cells.
• Explain the difference between unicellular and multicellular organisms.
• Write a short report describing how your investigation provided evidence that living things are made of cells.
• Create a diagram showing cells in a unicellular and a multicellular organism with labels.

Answer Guide

• What is a cell?
  Answer: A cell is the smallest unit of life that can carry out all the processes necessary for living things.
• How can you tell if something is living or non-living by looking at it under a microscope?
  Answer: Living things have cells visible under a microscope, while non-living things do not have cells.
• Describe the difference between unicellular and multicellular organisms and give an example of each.
  Answer: Unicellular organisms are made of one cell, like bacteria or some pond organisms. Multicellular organisms have many cells with different types, like plants and animals.
• Explain how observing cells in different organisms helps us understand the diversity of life.
  Answer: Observing cells shows that some organisms are single-celled while others have many specialized cells, which helps us understand how life varies in complexity and function.
• Design a simple investigation to provide evidence that living things are made of cells, including what you would observe and how you would record your evidence.
  Answer: Use a microscope to observe samples of pond water and plant leaves. Record detailed drawings and notes of cells seen in living samples and compare to non-living samples. Use observations to explain that living things are made of cells.

Real-Life Application

Encourage students to observe living things at home or outside, such as plants or insects, and describe what they think their cells might look like based on what they learned.

Homework or Home Connection

• Encourage students to observe living things at home or outside, such as plants or insects, and describe what they think their cells might look like based on what they learned.

Lesson Summary

Students conducted investigations using microscopes to observe cells in living organisms and compared them to non-living things. They gathered evidence that all living things are made of cells, either one cell or many different types and numbers of cells. Through observations, discussions, and explanations, students developed a foundational understanding of the cellular basis of life, distinguishing living from non-living based on cellular structure.

Teacher Notes

Use the exact standards alignment and retrieved-source provenance stored with this enrichment.

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