OBSERVING AND COLLECTING DATA

• Our understanding of the world around us is based on observations. Observing is the use of one or more of the five senses to perceive objects or events. For example, you will use your sense of sight to observe any turbidity changes in your aquarium.

• Scientists also use a variety of tools to aid in making observations. In these experiments you will be using tools such as a hydrometer to test fluid density, as well as a variety of water quality test kits which will be used to monitor such factors as nitrates, phosphates and dissolved oxygen levels in your tank.

• While making observations, scientists often collect data. Collecting data is the gathering and recording of specific information based on observations. You will be recording and sharing your aquarium observations with your class mates and students conducting this experiment at other schools.

MEASURING

• Observations are most useful when they involve quantitative data --- data that can be measured in numbers. Measuring is the process of determining the dimensions of an object , the number of objects in a group, the duration of an event, or other characteristics in precise units.

• For example, the water quality test kits that you will be using in this investigation measures dissolved oxygen in the 1 - 12 mg/L range. The fact that this measurement is quantitative will make interpreting the data easier, resulting in more precise conclusions about the events in your aquarium pertaining to dissolved oxygen.

 

ORGANIZING DATA

• Data is of little use unless it is organized. Organizing data involves placing observation and measurements in some kind of logical order, such as in a graph, chart, table, or a map. This is an essential part of the Scientific Process which assists in the interpretation of the data. During this investigation you will be organizing your data into graphs, charts and tables which will be shared with others students who are also involved with this project.

 

HYPOTHESIZING

• Hypothesizing is the process of forming testable statements about observable phenomena. This is often one of the first steps in a scientific investigation. A statement is testable if evidence can be collected that either supports the hypothesis or refutes it. If you hypothesized that the nitrate level in your aquarium would increase over time, yet the data collected showed a decrease your hypothesis would be considered false. It is important to note that although a hypothesis may be refuted, it can never be proved true beyond all doubt. At any time new data may be collected that indicates a previously accepted hypothesis does not hold true in all instances. It is for this reason the statement, “ I have proven my hypothesis” should not be used when writing a conclusion. At best, a hypothesis is strengthened by evidence which supports it.

 

PREDICTING

• To test a hypothesis, a scientist usually makes a prediction that follows from the hypothesis. Predicting is stating in advance the results that will be obtained from testing a hypothesis. A prediction can take the form of an “if - then” statement. You might make the following predictions based on the hypothesis discussed above. If it is true that the nitrate level in the aquarium increased over time, then I will observe a rise in the nitrate level of the tank as compared to day one of testing. If the data collected shows this prediction to be false the hypothesis is refuted. If the data shows this prediction to be true the hypothesis is supported.

 

EXPERIMENTING

• Some hypotheses or predictions can best be tested through careful observations in a natural setting, such as a field study. Others can be tested through experiments. Experimenting is the process of testing a hypothesis or prediction by carrying out data-gathering procedures under controlled conditions. Such conditions eliminate extraneous influences and allow close observations to be made.
• Most experiments in biology are controlled experiments. A controlled experiment is based on a comparison of a controlled group or phase with an experimental group or phase. The control group and the experimental group are designed to be identical except for one factor. This factor is called the independent variable or the manipulated variable. During the course of a controlled experiment, a scientist observes or measures one main factor in both the control group and the experimental group. This factor is called the dependent variable or the responding variable.

 

ANALYZING DATA

• After a scientist has collected and organized data from a field study or an experiment, the data must be analyzed. Analyzing data is the process of determining whether or not the data is reliable and whether or not it supports a given prediction or hypothesis. Scientists analyze data in many ways, including using statistics, interpreting graphs, determining relationships between variables, comparing the data to those obtained from other studies, and determining possible sources of experimental error.
• For example, suppose that you are in charge of the nitrate level data for your class. In analyzing this data you might average the nitrate level collected in the ten gallon tanks and compare them to the average nitrate level of the five gallon tanks. By graphing these averages over time you are now in a better position to make some conclusions about the nitrate levels over time in the two tanks and to determine whether or not the data refuted your hypothesis.

 

INFERRING

• Inferring is the process of drawing conclusions on the basis of facts or premises instead of direct perception. Facts might include data gathered during a field study or an experiment. Premises might include conclusions drawn from previous knowledge or from past experience.
• Some inferences, such as the change in nitrate level in an aquarium over time, are theoretically testable. However, other inferences are not. For example, suppose a biologist notices that two horse fossils show many similarities in structure. Further analysis might indicate that one fossil is 30 million years old and the other is 20 million years old. Based on knowledge of evolution, the biologist might infer that the older species is ancestral to the younger species. Even though this may be true, the inference are not testable because it is based on events that would have occurred millions of years ago and therefore are not directly observable.

 

MODELING

• Modeling involves constructing a representation of an object, a system, or a process that helps show relationships between data. A model may be visual, verbal, or mathematical. A biologist might create a mathematical model to show how environmental factors, such as sunlight, temperature, rainfall, and humidity , affect the growth of plants in the rain forest. Scientist sometimes use models to help generate new predictions or hypotheses.

 

COMMUNICATING

• Scientist do not work in isolation. Often they work in groups. In many cases they publish results of their experiments in scientific journals or present them at scientific meetings. Sharing information, or communicating, is essential to progress in science. Communication allows scientists to build on the work of others.
• In this experiment you will be sharing your results with other classes and schools who are working on the same project. You will also be able to view and analyze other student’s work to aid and assist your research.