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1.1: Science and the Natural World

Difficulty Level: At Grade Created by: CK-12
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Key Concept

The goal of science is to understand the natural world through systematic study, using evidence and logic. A scientific investigation is a plan for asking questions and testing hypotheses. A scientific theory is a broad explanation that is widely accepted because it is supported by a great deal of evidence.


  • CA.9–12.IE.1.b, c, d, f, g, j, k, n
  • NSES.9–12.A.1.1, 2, 4, 6; NSES.9–12.A.2.1, 2, 5, 6; NSES.9–12.E.2.3; NSES.9–12.G.2.1, 2, 3; NSES.9–12.G.3.2, 3, 4
  • AAAS.9–12.1.A.1, 2, 3; AAAS.9–12.1.B.1, 2, 3, 4, 6, 7; AAAS.9–12.1.C.4, 7; AAAS.9–12.11.B.1, 2, 3; AAAS.9–12.12.A.1, 2; AAAS.9–12.12.D.5
  • McREL.9–, 2, 3, 4, 5; McREL.9–, 2, 3, 4, 5, 6, 7; McREL.9–, 2, 3, 4, 5, 6, 7, 8; McREL.9–, 2; McREL.9–, 2, 3, 4, 5, 6, 7, 8; McREL.9–, 2, 3, 4, 5; McREL.9–, 2, 3, 4; McREL.9–, 2, 3,4; McREL.9–, 17, 18, 20, 22; McREL.9–, 8, 9; McREL.9–; McREL.9–, 8; McREL.9–, 3, 4, 5

Lesson Objectives

  • Identify the goal of science.
  • Describe how scientists study the natural world.
  • Explain how and why scientists do experiments.
  • Describe types of scientific investigations.
  • Explain what a scientific theory is.

Lesson Vocabulary

  • dependent variable: variable in a scientific experiment that is affected by another variable, called the independent variable
  • evidence: any type of data that may be used to test a hypothesis
  • experiment: special type of scientific investigation that is performed under controlled conditions
  • hypothesis: possible answer to a scientific question that can be proven false
  • independent variable: variable in a scientific experiment that is manipulated by the researcher to investigate its affect on another variable, called the dependent variable
  • model: representation of part of the real world
  • observation: anything that is detected with the senses
  • prediction: statement that tells what will happen under certain conditions
  • science: distinctive way of gaining knowledge about the natural world that tries to answer questions with evidence and logic
  • scientific investigation: plan for asking questions and testing possible answers
  • scientific law: statement describing what always happens under certain conditions in nature
  • scientific theory: broad explanation that is widely accepted as true because it is supported by a great deal of evidence

Teaching Strategies

Introducing the Lesson

Describe a common activity such as comparison-shopping. Guide students in identifying how it is similar to science. (Both involve posing questions, making observations, analyzing data, and drawing conclusions.)

Building Science Skills

Have students watch the video demonstrations at the links below. Ask them to predict what will happen in each demonstration. Challenge the class to brainstorm hypotheses to explain their observations.

Differentiated Instruction

Instruct students to start a word wall for biology. For each lesson, beginning with this one, select a few students to add some or all of the new vocabulary terms to the wall. They should include definitions, examples, or illustrations of the terms. ELL, LPR


Ask interested students to investigate landmark scientific discoveries in biology (e.g., Van Leeuwenhoek’s discovery of microorganisms; Krebs’s discovery of the Krebs cycle; Watson, Crick, and Franklin’s discovery of the structure of DNA). Give students an opportunity to share what they learn with the class. Ask them to explain how the discoveries were made and how they affected the direction of science. These and other discoveries are described at the link below.

Science Inquiry

Divide the class into groups, and ask each group to develop a research plan to test the same hypothesis (e.g., plants will bend in order to face the light). Their plan should include independent and dependent variables and controls. Give groups a chance to share their ideas and discuss their merits.

Common Misconceptions

Read the statements below to the class. Ask students whether they think the statements are true or false. Then explain why each of the statements is a misconception. For more information, go to this link: http://undsci.berkeley.edu/teaching/misconceptions.php

  1. There is a single scientific method that all scientists follow.
  2. Science is based only on data and involves no creativity.
  3. Without an experiment, a study is not scientific.
  4. Scientific ideas are always changing so they can't be trusted.
  5. Scientific data can prove that hypotheses are true or false.

Reinforce and Review

Lesson Worksheets

Copy and distribute the lesson worksheets in the CK-12 Biology Workbook. Ask students to complete the worksheets alone or in pairs as a review of lesson content.

Review Questions

Have students answer the Review Questions listed at the end of the lesson in the FlexBook®.

Points to Consider

The Points to Consider at the end of each lesson in this book will help you relate what you just learned to what is coming next. The questions will help guide you to the next lesson or chapter. Before reading the next lesson of this chapter, consider these points:

  • Remember the opening photo of red blood cells and green viruses? The blood cells are cells of a living thing. Do you think that the viruses are living things? Why or why not?
  • Lab experiments are the main method of gathering evidence in some branches of science. Why might lab experiments not be the best way to study living things, such as wild animals?

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