TEKS Addressed: 8.1A, 8.1B, 8.2A, 8.2B, 8.2C, 8.2D, 8.2E, 8.3A, 8.4A, 8.4B

Introduction

This unit bundles Student Expectations that address the application of experimental investigation in a new or novel context. The process of building scientific understanding involves the examination and discovery of concepts through student-designed scientific inquiry and research.

Prior to this Unit

• Grade 5

  • 5.2A – Describe, plan, and implement simple experimental investigations testing one variable.

• Grade 6

  • 6.2B – Design and implement experimental investigations by making observations, asking well defined questions, formulating testable hypotheses, and using appropriate equipment and technology.

• Grade 7

  • 7.2B – Design and implement experimental investigations by making observations, asking well defined questions, formulating testable hypotheses, and using appropriate equipment and technology.

• Grade 8

  • 8.2B – Design and implement experimental investigations by making observations, asking well defined questions, formulating testable hypotheses, and using appropriate equipment and technology.

During this Unit

The intent of this unit is not to teach all of the process skills in isolation. Rather, it is a unit that allows students to apply the knowledge that they have obtained throughout the year in a new context that prepares them for high school science. Safety guidelines and a brief review of scientific practices should have been established at the beginning of the year, so that students are aware of protocol and how to think critically. These concepts should have been reinforced throughout the school year. Students design and implement experimental investigations testing one variable. This will involve designing a fair test in which a control is identified. This includes formulating and developing a hypothesis, writing procedures, selecting and using equipment, collecting data, analyzing and interpreting results, and communicating valid conclusions. Students may only change one variable (independent or cause) while keeping all other conditions the same. The dependent variable (effect) is observed or measured in an effort to gather evidence to support or not support a causal relationship. Furthermore, students demonstrate safe practices as outlined in the Texas Education Agency-approved safety standards and consider environmentally appropriate and ethical practices with resources during investigations.

After this Unit

Students will engage in experimental design throughout their high school course work.

Additional Notes

STAAR Note

This unit should occur after administration of the Grade 8 STAAR. The application of Student Expectations in this unit are foundational to high school Scientific Investigation and Reasoning Student Expectations that will be incorporated into at least 40% of the test questions on the Biology EOC STAAR.

Research

At this level, students need to become more systematic and sophisticated in conducting their investigations, some of which may last for weeks or more. That means closing in on an understanding of what constitutes a good experiment. The concept of controlling variables is straightforward but achieving it in practice is difficult. Students can make some headway, however, by participating in enough experimental investigations (not to the exclusion, of course, of other kinds of investigations) and explicitly discussing how explanation relates to experimental design.

Student investigations ought to constitute a significant part—but only a part—of the total science experience. Systematic learning of science concepts must also have a place in the curriculum, for it is not possible for students to discover all the concepts they need to learn, or to observe all of the phenomena they need to encounter, solely through their own laboratory investigations. And even though the main purpose of student investigations is to help students learn how science works, it is important to back up such experience with selected readings. This level is a good time to introduce stories (true and fictional) of scientists making discoveries—not just world-famous scientists, but scientists of very different backgrounds, ages, cultures, places, and times.

“By the end of the 8th grade, students should know that:

• Scientists differ greatly in what phenomena they study and how they go about their work. 1B/M1a

• Scientific investigations usually involve the collection of relevant data, the use of logical reasoning, and the application of imagination in devising hypotheses and explanations to make sense of the collected data. 1B/M1b*

• If more than one variable changes at the same time in an experiment, the outcome of the experiment may not be clearly attributable to any one variable. It may not always be possible to prevent outside variables from influencing an investigation (or even to identify all of the variables). 1B/M2ab

• Collaboration among investigators can often lead to research designs that are able to deal with situations where it is not possible to control all of the variables. 1B/M2c*

• What people expect to observe often affects what they actually do observe. Strong beliefs about what should happen in particular circumstances can prevent them from detecting other results. 1B/M3ab

• Scientists know about the danger of prior expectations to objectivity and take steps to try and avoid it when designing investigations and examining data. One safeguard is to have different investigators conduct independent studies of the same questions. 1B/M3cd”

American Association for the Advancement of Science. (2009). Benchmarks on-line. Retrieved from http://www.project2061.org/publications/bsl/online/index.php?chapter=1#B2.

Laboratory investigations are essential for the effective teaching and learning of science. A school laboratory investigation (“lab”) is an experience in the laboratory, classroom, or the field that provides students with opportunities to interact directly with natural phenomena or with data collected by others using tools, materials, data collection techniques, and models.

National Research Council (NRC). 2006. America’s lab report: Investigations in high school science. Washington, DC: National Academy Press (p. 3).

“Inherent in laboratory-based activities is the potential for injury. Studies show that safety in K–12 school science instruction needs immediate and significant attention.”

National Science Teachers Association. (2010) NSTA position statement: Liability of science educators for laboratory safety. Retrieved from http://www.nsta.org/about/positions/liability.aspx.