[ Secondary Science Instruction ]


What's in the Water?

Activities Using Computer Based Labs with Probes to Acquire Data




[ Temperature | pH | Dissolved Oxygen | Turbidity | Nitrates and Phosphates ]

Part D: Turbidity

Overview/Introduction:

Turbidity is the amount of muddiness or cloudiness in the water usually caused by stirring up of sediments. Light reflects off of particles in the water producing a cloudiness. Turbidity affects the amount of sunlight reaching aquatic plants and therefore affects the entire aquatic food chain by affecting the amount of oxygen available. Oxygen content of aquatic ecosystems is perhaps the single most important factor in the ecological health. Lower oxygen reduces biodiversity. Many factors including turbidity, affects oxygen content. These include eutrophication caused by unnaturally high nutrient levels, temperature, plant growth, surface area. Purpose or Objective:

  1. To conduct a test to determine the turbidity of water samples.

Time Required: One period

Materials, Tools, and Resources Needed: CBL (Vernier, Pasco, etc.) with turbidity probe, Graphing calculators or lap top computer, Turbidity probe, Cuvettes, Sampling bottles, Distilled water.

Teacher Preparation:

Collect water samples from local bodies of water. If the water sample is not turbid enough, "create" a sample by adding a little cornstarch to the water as a demonstration.

Time Frame: one period

Procedure for CBL (see CBL manual for complete instructions):

  1. Connect the turbidity sensor into the CBL interface. Use the link cable to connect the graphing calculator or lap top to the interface.

  2. Turn on the calculator or lap top and start the data program.

  3. Select and calibrate the turbidity sensor.

  4. Invert the water sample cuvette several times to mix particles. Tap the bottom of the cuvetter to release any air bubbles.

  5. Place the cuvette into the turbidity sensor and select START to begin the operation.

  6. The turbidity value in NTU (Nephelometric Turbidity Unit) will appear on the screen after 10 seconds.

  7. Repeat step 6 for additional samples.

    RECORD your data on the chart.

Student Handouts/ Record Sheets

  1. Data chart

Student Discussion Questions:

  1. What are some biological factors that can affect the turbidity of a body of water? How does high turbidity affect plant growth? How does high turbidity affect the amount of oxygen available to consumers?

  2. What are some of the geologic factors that can affect the turbidity of a body of water? What weather conditions may affect the turbidity?

  3. What are some of the ways that human action can affect turbidity of a body of water?

  4. Sometimes when you turn on the tap, the water may appear cloudy. What do you think may have accounted for this?

Grade 9-12

California Science Content Standards

Acids and Bases

5. Acids, bases, and salts are three classes of compounds that form ions in water solutions. As a basis for understanding this concept:

  •  
    		•  Students know the observable properties of acids, bases, and salt solutions.

  •  
    		•  Students know acids are hydrogen-ion-donating and bases are hydrogen-ion-accepting substances.

  •  
    		•  Students know how to use the pH scale to characterize acid and base solutions.

    Solutions

    6. Solutions are homogenous mixtures of two or more substances. As a basis for understanding this concept

  •  
    		•  Students know the definitions of solute and solvent.

  •  
    		•  Students know how to calculate the concentration of a solute in terms of grams per liter, molarity, parts per million, and percent compositions

    Ecology

    6. Stability in an ecosystem is a balance between competing effects. As a basis for understanding this concept:

  •  
    		•  Students know how to analyze changes in an ecosystem resulting from changes in climate, human activity, introduction of nonnative species, or changes in population size.

  •  
    		•  Students know how water, carbon, and nitrogen cycle between abiotic resources and organic matter in the ecoystem and how oxygen cycles through photosynthesis and respiration.

    Investigation and Experimentation

    Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and to address the content in the other four strands, students should develop their own questions and perform investigations. Students will:

    a. select and use appropriate tools and technology (such as computer-linked probes, spreadsheets, and graphing calculators) to perform tests, collect data, analyze relationships, and display data.

    National Education Technology Standards for All Students

    3. Technology productivity tools

    Students use technology tools to enhance learning, increase productivity, and promote creativity.

    Technology research tools

  •  
    		•  Students use technology to locate, evaluate, and collect information from a variety of sources.

  •  
    		•  Students use technology tools to process data and report results.

  •  
    		•  Students evaluate and select new information resources and technological innovations based on the appropriateness to specific tasks.

    Technology problem-solving and decision-making tools

  •  
    		•  Students use technology resources for solving problems and making informed decisions.

  •  
    		•  Students employ technology in the development of strategies for solving problems in the real world.

     

     

     

     

     


    The Integrating Technology into Science Instruction webpages project is partially funded by grants from The Boeing Company and The Ralph M. Parsons Foundation. Integrating Technology into Instruction is a project of Target Science (target@laep.org) and is displayed on the Los Angeles Educational Partnership Learning Exchange. Target Science is an initiative of the Los Angeles Educational Partnership.
    Updated August 2000