Scientific Inquiry Section 1: Length & Measurement ruler or meter stick: equipment used in the lab to measure length in millimeters, centimeters or

Transcription

1 Scientific Inquiry Section 1: Length & Measurement ruler or meter stick: equipment used in the lab to measure length in millimeters, centimeters or meters. meter: metric unit for length -Scientists use a ruler or meter stick to measure length in metric units instead of feet and inches. The ruler or meter stick has several types of marks. The smallest marks indicate millimeters (mm). These marks are also known as graduation marks and are found on many types of scientific equipment. -There are 10 mm in a centimeter (cm); 1000 mm in a meter (m); 100 cm in a meter; 1000m in a kilometer (km). One mile is approximately 1.6 km.

2 -Rulers and meter sticks require you to determine measurement by sight, not by digital readout. In cases where the measurement falls between 2 graduations, you simply estimate between the marks. -Scientists always want to be accurate and often want to be precise, but accuracy and precision are not the same thing. accuracy: the correctness of a measurement or how close the measurement is to the actual value precision: the exactness of a measurement in terms of how many decimal places are used; determined by the smallness of the increments used in the measurement. - For example, 3.2kg is more precise than 3 kg.

3 Rules for Accuracy & Precision 1. The more numbers after the decimal, the more precise the measurement. 2. The greater the number of graduations on a measuring device, the greater the precision of the device. Section 2: The Scientific Method - The scientific method is a series of steps in logical order that scientists use to help them solve a problem. 1. Make an observation. 2. State the problem. 3. Form a hypothesis. 4. Create and conduct an experiment. 5. Collect data.

4 6. Form a conclusion.* 7. Publish and share information. *If the hypothesis is not proven, form a new hypothesis and repeat steps 4-7. problem: an observation that needs an explanation or a question that needs an answer. The problem begins with an observation using the 5 senses - hearing, smelling, touching, tasting and seeing. What do you want to find out? What do we already know about it? hypothesis: a possible explanation or answer to a scientific problem that can be tested. In other words, the hypothesis is a possible reason for the problem. It must be testable and logical. e.g. "Corn plants that get more direct sunlight grow taller." "Goldfish will grow longer in a larger aquarium." "A curve ball curves because of the Bernoulli effect."

5 experiment: a step-by-step procedure used to test the hypothesis. It includes dependent and independent variables, the controls (or constants), and types of data collected. conclusion: based on the data, was your hypothesis correct? If it was not correct, can you develop a new hypothesis to test? theory: an idea that is accepted as true because so much evidence supports it. If experiments are repeated under similar conditions and obtain similar results, they may lead to a theory. -Not all scientific questions can be answered by conducting an experiment, such as: What flavor of ice cream is best? Who is the greatest super hero - Spiderman, Superman, or Batman? Should scientists clone humans?

6 Should seed companies modify the genetics of plants? *Remember, science deals with facts, not opinions or hearsay. Section 3: Setting Up Experiments data: any information gathered during an experiment. Data can be classified into two categories - quantitative and qualitative. The two sound similar, but are quite different. 1. quantitiative data: data that deals with numbers or amounts, such as measurements like length, mass, ph, temperature, or time of day. This type of data is the most recorded type of data in experiments. Quantity is an amount of something, so quantitative data deals with numbers or amounts.

7 2. qualitative data: data that is descriptive, such as color, odor, taste, feel, or any other described quality. -There are two types of groups used in scientific experiments - a control group and an experimental group. 1. control group: This group serves as a standard for comparison. It is treated exactly the same as the experimental group or groups except it will not receive the element being tested. 2. experimental group: This group is treated exactly the same as the control group except it will receive the element being tested. It cannot receive more than one testing element; otherwise it will not be possible to determine how each element affected the group. e.g. If

8 you wanted to test how fertilizer effects tomato plants, you could not add fertilizer and change the soil type. You would only add the fertilizer and keep my soil type the same. -Whenever possible, each group in an experiment should be made up of more than one member. By having multiple members in a group, individual differences among members average out. Additionally, more members in each group increase the validity (or truth) of the experiment since each member represents additional experiment attempts. bias: is a belief or a preference for a specific outcome. unbiased: means a person does not let his or her personal opinions affect the results.

9 -When performing an experiment, a scientist should be unbiased, or impartial. For example, let's say a research scientist believes she found a new drug that will cure cancer. The scientist will have a strong belief (a bias) that this drug works, and her belief (bias) may influence her own experimental results. placebo: an inert substance (has no effect) given to the control group that should have no effect on the control group. The purpose of a placebo is to eliminate biases. Placebos are often given in experiments involving people because the attitudes of people can be a factor in the experiment. placebo effect: the belief that a person is experiencing an effect when in fact, they are not. e.g. People who think they are receiving

10 medication, but are given a placebo (which has no medication), can sometime improve a health condition just because they believe that they are receiving the medication. -In a well-performed experiment, it is extremely important that all groups are treated exactly the same except for the experimental element. All the other elements that are the same are called controls or constants. control (or constant): elements in an experiment that must be considered and kept the same or else they may affect the results of the experiment. e.g. If you wanted to test the effect of fertilizer on tomato plants, some of the control elements would be the type of soil, the amount of sunlight, the amount of water, and the number of plants in each group.

11 -Where items for an experiment are purchased would not be a control for an experiment as long as the items are the correct ones needed to conduct the experiment. variables: things that change during an experiment. One variable is tested in each experimental group. No more than one variable should be tested per group at one time. There are two types of variables that are important in an experiment: independent (or manipulated) and dependent (or responding) variable. 1. independent (manipulated) variable: the element that the experimenter uses or changes to produce results. 2. dependent (responding) variable: the measured change caused by the independent variable.

12 -e.g. "By using fertilizer, the tomato plants will produce more tomatoes." In the hypothesis, the independent variable is the fertilizer because it is being used to produce a result. The dependent variable is the number of tomatoes because it is the measured change caused by the fertilizer. -Just remember that the dependent variable depends on the independent variable.