STUDENT LABORATORY PACKET. Student s Full Name LAB # 2: Observations and Inferences Lab Instructor Date POINTS

Transcription

1 L2 - Observations & Inferences Page 1 of 6 STUDENT LABORATORY PACKET Student s Full Name LAB # 2: Observations and Inferences Lab Instructor Date POINTS OBJECTIVE: To learn how to make scientific observations NYS Standards: COMMON CORE STANDARDS: Reading: 2, 3, 4, 7; Writing: 2f BACKGROUND: Miller, K.R. and Levine, J. (2006) Biology p. 4 (dragonfly textbook) In order for scientists to understand the natural world and draw logical conclusions from their experiments, they must make accurate observations, which require the use of our senses. The five senses are used to make observations about natural phenomen Scientists can use their five senses directly (hear, smell, sight, etc.), or use instruments to help expand their senses (noise detectors, gas chromatography, spectrometer, etc). There are two types of observations - quantitative and qualitative. Scientists prefer quantitative observations, which are measurable. This makes your data more objective and less subject to personal prejudices. When observations involve using our visual sense, scientists need to record accurately what is seen. Therefore, it is important to observe closely and draw accurately. A drawing is usually a composite of many observations of a related specimen. The drawing must convey effectively the information you want to pass on to the viewer. When drawing (1) use a pencil, not a pen; (2) position the diagram, so there is enough space to draw and label all the parts; (3) draw the diagram large enough to see all of the parts, do not crowd; (4) be accurate, not stylized; draw what is seen in the same relative proportion (use a ruler if necessary, and all lines should meet not floating into space); (5) use simple lines, no shading; and (6) label a title, magnification, scale, name of structures. If you are drawing a magnified specimen, draw only 2-4 cells, not all the cells in the field of vision. A trick to help you draw in proportion is to think of drawing on a grid. Superimpose mental graph paper on the specimen you are observing. See the sample drawing below. Actual specimen viewed under a microscope An unacceptable drawing of that specimen

2 L2 - Observations & Inferences Page 2 of PRE LAB (Do Prior to Coming to Lab) What is the difference between a quantitative and a qualitative observation? Answer in the table below. Give an example of each. Type of Observation Definition Example Quantitative observation Qualitative observation 2. Write any two observations you made today in the table below. Next to each, state whether it is quantitative or qualitative. (Should not refer to the peanut.) Quantitative or Observation Qualitative 3. What is an inference? 4. Make an inference using one of the observations you listed in question # 2a or b: 5. Given the following statements in the table below, decide whether each is an observation or an inference: Statement The shell has a rough surface. There are two peanuts in the shell. The surface markings on the shell are in rows, running lengthwise. Observation or inference

3 L2 - Observations & Inferences Page 3 of LAB MATERIALS: 6-8 peanuts (in their shell), metric and English units ruler, piece of string, triple beam balance, and digital balance, calculator PROCEDURE: 1. Select a container of peanuts for your group. Do not mark the peanuts. Each member of the group should pick one peanut at random from the container. c. Examine the peanut; make sure that it is not discolored or broken. (Select another if this is the case). d. Draw a detailed and accurate diagram (lengthwise) of your peanut in the box below. Refer to the pre-lab for drawing criteri Do not just outline your peanut. 2. Make 4 qualitative observations about your peanut: Write your observations below. Make sure your observations are not inferences. Note: although we encourage your creative observations, do not attempt to taste your peanut! Qualitative Observations 1. Sight: 2. Touch: 3. Smell: 4. Sound: 3. Make the following quantitative observations/do the actual measurements. (Make sure to include units). Do not convert between the English and Metric systems of measurements. Quantitative Observations LENGTHS Length of peanut in inches* Length of peanut in centimeters Length of peanut in millimeters MASS Mass of peanut in grams (triple beam balance) Mass of peanut in grams (digital balance) *Note: Length is measured to the nearest 1/16 th of an inch or 1.0 millimeter. Mass is measured to the nearest 0.1 gram 4. Re-examine your observations in steps 2 and 3 above. Write two inferences that might be made from your any of your observations. Record your inferences below.

4 L2 - Observations & Inferences Page 4 of 6 CONCLUSIONS: 1. What methods (how) did you use to determine the qualitative observations? 2. What methods (how) did you use to determine the quantitative observations? 3. How is an inference related to an observation? 4. Which do you think is more reliable, an inference or an observation? Why? 5. Why is careful observation and recording of information important in science? 6. In determining the weight of your peanut, was there a significant difference between using the two different instruments? Explain your answer. (Hint: Remember that accuracy is based on the condition of the apparatus/ balance and the number of significant figures the apparatus is able to measure.) EXTRA CREDIT: Must show all work How much taller are you than a peanut? Make a mathematical comparison of your height to the length of your peanut. Show all your work below. Determine your height in mm. Remember to indicate units. (Clue: 1 inch = 2.54 cm) Determine your height in inches What is the conversion factor for changing inches to centimeters? Using the conversion factor, what is your height in centimeters? What is the conversion factor for changing centimeters to millimeters? Using the conversion factor, what is your height in millimeters? Final value: Your height in millimeters. Make a ratio between your height and the length of your peanut in millimeters. (For example: if you were twice as tall as your peanut, you would record a ratio of 2:1). Reduce the ratio to the lowest terms and round off to the nearest whole number. Your height in millimeters Your peanut s length in millimeters Divide your height by the length of your peanut Round off to the nearest whole number Express as a ratio (? : 1 ) Final value: your height to the length of a peanut in mm (no units here). Please remember to copy your data and conclusions over onto the Student Answer Packet. Only these sheets will be collected and graded. You will need your copy to study for the lab quizzes. Even though you worked with a lab group, your answers should be unique.

5 L2 - Observations & Inferences Page 5 of 6 Student Answer Packet Student s Full Name LAB # 1: Peanuts Lab Instructor Date Points FINAL GRADE Pre-Lab Completed as homework: Max. value 1pt. pt. Data: Max. value 5 pts. pts. 1. Drawing of peanut Sight: Qualitative Observations 2. Touch: 3. Smell: 4. Sound: 3. LENGTHS Length of peanut in inches* Length of peanut in centimeters Length of peanut in millimeters Quantitative Observations MASS Mass of peanut in grams (triple beam balance) Mass of peanut in grams (digital balance) *Note: Length is measured to the nearest 1/16 th of an inch or 1.0 millimeter. Mass is measured to the nearest 0.1 gram 4. Making two inferences based on above observations.

6 L2 - Observations & Inferences Page 6 of 6 Conclusions: Max. value 4 pts. pts. 1. What methods (how) did you use to determine the qualitative observations? 2. What methods (how) did you use to determine the quantitative observations? 3. How is an inference related to an observation? 4. Which do you think is more reliable, an inference or an observation? Why? 5. Why are careful observation and recording information important in science? 6. In determining the weight of your peanut, was there a significant difference between using the two different instruments. Explain your answer. (Hint: Remember that the accuracy is based on the condition of the apparatus/ balance and the number of significant figures the apparatus is able to measure.) EXTRA CREDIT: MUST SHOW ALL WORK pts. (1 pt. max.) How much taller are you than a peanut? Determine your height in inches What is the conversion factor for changing inches to centimeters? Using the conversion factor, what is your height in centimeters? What is the conversion factor for changing centimeters to millimeters? Using the conversion factor, what is your height in millimeters? Final value: Your height in millimeters. Your height in millimeters Your peanut s length in millimeters Divide your height by the length of your peanut Round off to the nearest whole number Express as a ratio (? : 1) Final value: your height to the length of a peanut in mm (no units here).