Unit 1 Measurement, Graphing, Scientific Method, and Lab Tools

Safety in the Lab What are some ways you can improve safety in the lab? Lab safety video (7.07)

Part 1: Measurement Scientists use different instruments in order to collect data. The metric system is used in science.

Reading Thermometers Used to measure the amount of heat energy something has Units are degrees Celsius ( 0 C)

Reading a Thermometer 1.Figure out what each line is worth 2.Find where the red mark goes to 3.Determine the temp. in deg. C. 4.What is the temp.?

Reading a Thermometer Each line is worth 2 degrees. Answer: In between 16 and 18, so it is 17 degrees C

Using a Metric Ruler Used to find the length and width of an object. Units are meters (m), centimeters (cm), and millimeters (mm)

Using a Metric Ruler 1.Find the metric side of the ruler (not inches) 2.Line your object up with 0 cm, or see where it is lined up at 3.Find the measurement (little lines are mm)

Using a Metric Ruler Lined up with 0. Answer: 5.1 cm

Reading a Graduated Cylinder Used to find the volume. Volume is the amount of space something takes up Volume is read from the bottom of the curved line (meniscus) Units are liter (L) and milliliter (ML)

Read from bottom of the meniscus!!!

Step 1: Figure out what each line is worth Step 2: Read amount from the bottom of the meniscus Step 3: Find the volume and record the unit

Find the Volume: Each line is worth 0.2 ml So, the volume is 20.6 ml

Finding the Mass of an Object You can use a triple beam balance or digital scale to find the mass. Mass is the amount of matter something has Units are grams (g), kilograms (kg), milligrams (mg)

Triple Beam Balance

Digital Scale

Converting Units in the Metric System Kids Have Dropped Under Desks Converting Metrics KHDUDCM

Practice Converting Units 1. 1 m = ___________cm 2. 1 m = ___________mm cm = ________m mm =________cm cm = ________mm

Answers: 1. 1 m = 100 cm 2. 1 m = 1000 mm cm = m mm = 450 cm cm = 1302 mm

Part 2: Data Tables / Graphing Used to organize data Graph: Picture of a set of data Allows you to see (visualize) your data

Data Tables and Graphing 1. Basic Vocabulary: a.Independent Variable – the variable that you have control over in the experiment (‘I’ change) b.Dependent Variable – the variable that you are measuring in the experiment

Practice In my experiment, I measured the number of times the students heart beat per minute after jumping rope for 3 minutes. What is the independent variable? What is the dependent variable?

Practice What is the independent variable? Time What is the dependent variable? Number of heart beats per minute

2. Tables a. Used to organize the data you collect during an experiment. b. When given a list of experimental data, organize the information: The independent variable should be listed in increasing amounts List the corresponding values for the dependent variable next to them

Example: Plant height (cm) over time (days) Which one can you control – plant height or days to observe? This one goes in the left column Organize the following data into a table: 3 days – 10cm; 2 days – 8 cm; 5 days – 15 cm; 7 days – 20cm 7 days – 20cm

Answer

Graphing - Background When making a graph: 1. Label the axes – you need to use equal increments. For example – go by 1’s or 2’s or 5’s – whatever will work and fit the best! 2. Plot the points using the data table 3. Connect the points to make a line graph

The Effect of Time (seconds) on Distance (meters) Things to Know: 1.The independent variable goes on the X axis (horizontal) – time 2.The dependent variable goes on the Y axis (vertical) – distance 1.To give a title: ‘The Effect of X on Y’ - ‘The Effect of Time on Distance y x

Practice Time (sec.)Distance (meters)

Graphing: How to Read a Graph Once you have plotted your points and connected them, you may ‘read’ or interpret your graph. You can state the relationship between the variables. In your example, what is the effect of the independent variable on the dependent variable? As the time _________________ the distance _______

Answer As the time increases, the distance increases then decreases.

Part 3: Scientific Method Define the scientific method: A series of steps scientists use to solve a problem.

Scientific Method List the steps of the scientific method:

34 1.State/recognize the problem 2.Make a hypothesis (educated guess) 3.Conduct an experiment 4.Make observations (Record data; graphs) 5.State a conclusion 6.Repeat How long does it take to walk 50 m? I think it will take 2 minutes. Walk 50 m and time it. Record the time it took to walk 50 m. It actually took 3 minutes to walk 50 m. Do it again.

35 When setting up an experiment, you need: - a control : use as comparison; standard - a variable: what you’re testing - independent variable (I change it!) - dependent variable (what you measure; depends on the independent variable) independent variable)

36 Experiment Example 1. Problem: Do radish seeds grow taller in more light? 2. Hypothesis: Radish seeds will grow taller in more light. 3. Experiment: Controls (things that will be the same throughout the experiment) - type of radish seeds - amount of water - type of soil and pot

37 Variables: Independent variable: - - amount of light Dependent variable: - height of plant 4. Make Observations: Create data table using light amounts and plant heights Amount of light Height (cm) 3 hours of light 2 4 hours light4 5 hours light6

38 Amount of light (independent variable) Height of plant (dependent variable) Title: The Effect of the Amount of Light on Plant Growth

39 Experiment Example cont… 5. Conclusion: Plants grow better in more light 6. Repeat: Conduct the experiment again

2 ways to make the results of an experiment better (more reliable and valid) 1. Repeat the experiment To see if similar results occur each time 2. Use more subjects (what you are testing on) Allows for more data collection 40

After much experimentation… 41

42 Theory vs. Law Theory A hypothesis about a situation that is supported by repeated experiments Ex. Theory of Evolution Continental Drift (Debatable) Law A theory that never changes; theory that has been tested many times Ex. Gravity (Non-debatable)

Part 4: Lab Tools Used by scientists to study living and once-living things.

Tools of Biologists Chromatography: Separate out different substances from one another by their chemical or physical properties. DEMO!

Compound Light Microscopes Used to study living and non-living cells. Allows you to view specimens at 40x, 100x, or 400x their real size Can be used for viewing large cell organelles (nuclei, chloroplasts)

47 1. Eyepiece (Ocular Lens) 2. Body Tube 3. Nosepiece 5. Objective Lens 4. Arm 9. Coarse Adjustment 10. Fine Adjustment 6. Stage 12. Base 11. Light Source 7. Stage Clips 8. Diaphragm

Functions of Microscope Parts: 48

PartFunction 1. EyepiecePiece you look through and it magnifies 10X 2. Body tubeConnecting piece 3. NosepieceTurns the objective lens 4. ArmPart used to carry 49

PartFunction 5. Objective LensMagnify the object 6. StageWhere slide is placed 7. Stage ClipsHold slide in place 8. DiaphragmTurns to adjust the amount of light 50

PartFunction 9. Coarse AdjustmentMoves stage a lot to find object (low power only) 10. Fine AdjustmentGets object fine-tuned 11. Light SourceGives light 12. BaseUsed to carry 51

Practice using the microscope!!! 52

Determining magnification 53

54 Total Magnification Eyepiece x scanning = total magnification (10x)(4x) = 40x Eyepiece x low power = total magnification (10x)(10x) = 100x Eyepiece x high power = total magnification (10x)(40x) = 400x

55 Effects on Image Image is inverted (upside and backwards) Normal viewMicroscope view

56 Depth of Field Organisms are three dimensional (not flat) You can only look at one layer of an organism at a time Use the fine adjustment knob to look at the different layers of an object.

57 Resolution: the ability to tell the difference between two points that are very close together

58 Effects of Staining Why do we apply stains to microscope images? To enhance details of the object Ex. Methylene blue, iodine No stain Stained

59 Field of View When you look in the microscope, all that you see is called the FIELD OF VIEW As the magnification gets larger, the field of view gets smaller The image is “zoomed in” on which means you can’t see all the image at once

60 Field of View continued… Larger magnification but you see less of the object Smaller magnification but you see more of the object

Measurement under the microscope 61

62 Estimating Diameter of the Field of View

63 Measurement Under the Microscope Microscope images are measured in MICROMETERS!

1mm = 1000um So, you will either: DIVIDE by 1000 (move decimal place 3 times to the left) DIVIDE by 1000 (move decimal place 3 times to the left) MULTIPLY by 1000 (move decimal place 3 times to the right 64

Practice Converting mm to um mm to um (multiply by 1000; move decimal 3 places to right) um to mm (divide by 1000; move decimal 3 places to left) 65

Practice: 5 mm = ________________um 0.5 mm = _______________um 0.05 mm = ______________um mm = _____________um 66

Practice Converting um to mm 1000 um = _______________mm 100 um = ________________mm 10 um = _________________mm 1 um = __________________mm 67

Applicable NYS Standards Appendix A (Lab Check-list) Standard 1: Key Idea 1, Key Idea 2, Key Idea 3