Scientific Method and Graphing Competency 1 Scientific Method and Graphing

Important Safety Symbols Biohazard: organisms and other biological materials may be harmful to humans Radiation: radioactive material nearby

Important Safety Symbols Potentially harmful fumes Sharp object

Important Safety Rules Never smell anything directly from a test tube. Point test tube away face and gently waft gas toward nose.

Important Safety Rules Wash your hands and clean up your lab station after the experiment. When in doubt, just TELL THE TEACHER! Broken glassware or equipment Spills Injury Contact with chemical on skin or in eyes

Lab Equipment Graduated Cylinder Used to measure precise volumes of a liquid. To correctly measure volume, look at the bottom of the curved line called the meniscus. Make sure you are reading it at eye level! How many mL are in this graduated cylinder? Answer: 43.5

Lab Equipment Triple Beam Balance Measures the mass of objects

Lab Equipment Triple Beam Balance How to read: What is the total mass of of this object? 500 + 40 + 5.2 = 545.2

Lab Equipment Beaker Flask Both can be used for stirring, mixing, measuring and heating liquids

Lab Equipment Pipette Bunsen burner Used for transferring liquids and/or measuring small amounts of liquids (a few mL). Used for heating.

Scientific Method Listing the Steps Ask Question Do Background Research Construct Hypothesis Test with an Experiment Analyze Results Draw Conclusion Think! Try Again Report Results Hypothesis is True Hypothesis is False or Partially True Make an Observation Define the Problem Research the Problem State the Hypothesis Experiment to test Hypothesis Collect and Record Data Analyze Data Draw Conclusions Determine Limitations Report Results

Scientific Method Creating a Hypothesis A hypothesis is: An educated guess, trial answer, possible solution, prediction Must be a statement (usually in “If…then” format) Must be testable or measurable Is based on your research and previous experience

Scientific Method Creating a Hypothesis Step 1: Define the problem. Example: Does the temperature of water affect the amount of sugar that will dissolve in it? Step 2: Make a prediction, a.k.a. hypothesis. If the temperature of water is increased, then the amount of sugar that can be dissolved in it will increase.

A hypothesis must be testable! You must make a prediction that is measurable by an experiment. If you are not predicting a measurable outcome, there is no way to test the hypothesis.

How do you test a hypothesis? Experimenting Use a Controlled Experiment An experiment that tests only one factor at a time by using a comparison of a control group and an experimental group. Control Group The group that the scientist changes nothing in. The Control group is used for comparison. Experimental Group The group that the scientist has changed something. It is the variable in the experiment where you want to see how this condition affects something.

Setting up an Experiment: Control Group Example: Six bean plants are to be tested to see what happens if light is taken away. The all have the same type of container, the same amount of soil, and they will receive the same amount of water. Three will be placed in a sunlit window and 3 will be placed in a dark closet for 2 weeks. What is the control group? The plants in the sunlit window Why? Plants are naturally found in areas with at least some sunlight. Nothing was changed about their normal habitat regarding sunlight.

Setting up an Experiment: Control Group Example: Six bean plants are to be tested to see what happens if light is taken away. The all have the same type of container, the same amount of soil, and they will receive the same amount of water. Three will be placed in a sunlit window and 3 will be placed in a dark closet for 2 weeks. What is the experimental group? The plants in the dark closet. Why? Photosynthetic plants are not normally found in completely dark environments. The scientist wants to see how this change will affect this group of plants.

Setting up an Experiment: What is a variable? A variable is something that can be changed. In an experiment it is a factor that is different from one group to another. Controlled variables– (constants) All the variables that remain constant Independent variable– (manipulated variable) factor that is purposely changed Dependent variable– (responding variable) factor that may change because of independent variable; what scientist wants to observe

Independent Variable Example: Six bean plants are to be tested to see what happens if light is taken away. The all have the same type of container, the same amount of soil, and they will receive the same amount of water. Three will be placed in a sunlit window and 3 will be placed in a dark closet for 2 weeks. What is the independent variable? Light—the scientist purposely changes the amount of light available to the plants.

Dependent Variable Example: Six bean plants are to be tested to see what happens if light is taken away. The all have the same type of container, the same amount of soil, and they will receive the same amount of water. Three will be placed in a sunlit window and 3 will be placed in a dark closet for 2 weeks. What is the dependent variable? Plant growth—the scientist will observe and measure how much the plants grow as a result of the light and dark conditions

Controlled Variables (Constants) Example: Six bean plants are to be tested to see what happens if light is taken away. The all have the same type of container, the same amount of soil, and they will receive the same amount of water. Three will be placed in a sunlit window and 3 will be placed in a dark closet for 2 weeks. What are the constants? Same container, amount of soil, amount of water In a controlled experiment, you must keep everything the same except one variable!

Experiments must be VALID Results of an experiment are not reliable if the experiment is not conducted properly. When conducting an experiment, always make sure to: Complete at least 3 trials Only change one variable at a time Have a control group to compare with experimental group

What is wrong with this experiment? James wondered if music had an effect on plant growth. He set up an experiment where 25 bean plants were placed in a chamber where music was played and 25 bean plants were placed in an identical chamber where music was not played. He placed one chamber outside in the summer heat and one chamber he kept inside his house. He gave all plants the same amount of fertilizer, soil, and water. At the end of two weeks plant height was measured.

What is wrong with this experiment? James wondered if music had an effect on plant growth. He set up an experiment where 25 bean plants were placed in a chamber where music was played and 25 bean plants were placed in an identical chamber where music was not played. He placed one chamber outside in the summer heat and one chamber he kept inside his house. He gave all plants the same amount of fertilizer, soil, and water. At the end of two weeks plant height was measured.

Identify the Variables A study was done to see if leaves added to soil had an effect on tomato production. Tomato plants were grown in four large tubs. Each tub had the same kind and amount of soil. One tub had 15 kg of rotted leaves mixed in the soil and the second had 10 kg. A third tub had 5 kg and the fourth had no leaves added. Each tub was kept in the sun and watered the same amount. The number of kilograms of tomatoes produced in each tub was recorded. What is the control group? What is the experimental group? Independent variable: Dependent variable: Control variables: Tub with no added leaves. All tubs with added leaves. Different kg of leaves added to each tub Kg of tomatoes produced Same size tub, same type and amount of soil, same amount of sunlight and water

Identify the Variables Bart believes that mice exposed to microwaves will become extra strong. He decides to perform this experiment by placing 10 mice in a microwave for 10 seconds. He compared these 10 mice to another 10 mice that had not been exposed. His test consisted of a heavy block of wood that blocked the mouse food. He found that 8 out of 10 of the microwaved mice were able to push the block away. 7 out of 10 of the non-microwaved mice were able to do the same. He recorded how many mice could push the block away. What is the control group? What is the experimental group? Independent variable: Dependent variable: Control variables: 10 non-microwaved mice 10 microwaved mice microwave Number of mice that can push the block Number of mice kept same between groups, same block of wood

Graphing in Science Graphs help us visualize numerical data. There are 3 different types of graphs: Bar graphs Pie graphs Line graphs

Bar Graph A bar graph is used to show relationships between groups. The two items being compared do not need to affect each other. It's a fast way to show big differences. Notice how easy it is to read a bar graph. Question: On what day was the most chocolate milk sold? Answer: Wednesday

Circle Graph or Pie Graph A circle graph is used to show how a part of something relates to the whole. This kind of graph is needed to show percentages effectively. Question: Which day was the least chocolate milk sold? Answer: Thursday

Line Graph A line graph is used to show change over time. It's clear to see how things are going by the rises and falls a line graph shows.

Line Graph Question: On which day was there a drop in milk sales? Answer: Thursday

Graphing Experimental Results Identify the Variables Number and label each axis Plot the points Draw the graph Give your graph a title

Graphing Experimental Results: Identify the Variables

Microscopes Magnification Ocular Lens Total Magnification Low 4x 10x To move image to the left, move stage to the right. To move image to the right, move stage to the left. OPPOSITE! Your microscope has 3 magnifications: Low, Medium, and High. Each objective will have written the magnification. In addition to this, the ocular lens (eyepiece) has a magnification. The total magnification is the ocular x objective Magnification Ocular Lens Total Magnification Low 4x 10x 40x Medium 100x High 400x