The steps that scientists take to gather information and answer questions

1) Identify problem/Ask question 2) Conduct Research 3) Formulate a hypothesis 4) Experiment 5) Analyze results and make a conclusion 6) Retest if necessary

Asks a question What are you trying to solve? What is it that you want to know?

Use the following: – Books – Magazines – Reports – Experts – Your past experiences

Testable explanation for a question or problem Example: Tomato plants will show an increased growth rate when planted with a greater amount of fertilizer

Null Hypothesis (H 0 ): –Hypothesis of no difference or no effect –Example: Tomato plants will show no difference in growth rate when increasing the amount of fertilizer. If results are statistically significant, the null hypothesis can be rejected

Plan the design of your Experiment. Consider the following………

Three Types of Variables 1.Independent 2.Dependent 3.Controlled (constants)

1. Independent variable –The condition that is being changed/manipulat ed –This variable affects the outcome Compost 2. Dependent variable – Variable that responds to changes in the independent variable – What is measured (data) – “Depends on” the independent variable – Plant growth (cm)

3. Controlled Variables (AKA Constants) : –Factors that are kept the same –Ex. Species of tomato, amount of sunlight, amount of water, etc. Must keep all other variables controlled, so any changes seen are the result of the independent variable

Independent & Dependent Variables independent variable is plotted on the x-axis dependent variable on the or the y-axis independent dependent

An Experimental Group will be the group with the Independent Variable: In this example, the plants receiving the various amount of fertilizer. A Control Group is identical to the experimental group but without the Independent Variable In this example, they wouldn’t receive the fertilizer. A Control group is for Comparison.

Make a data table Label the sections of your table. Always put in the correct units given or being used # of DaysHeight of plant (0g fertilizer) Height of plant (50g fertilizer) Height of plant (100g fertilizer) 23 cm65 46 cm cm1813

Create a table, chart, or graph for numerical data Take data and use it for

Summary of what you found when you tested your hypothesis –Use DATA to support conclusion Was your hypothesis supported? What could have/did go wrong? –Things that could have caused abnormal results –Called sources of error

Lets put our knowledge of the Scientific Method to a realistic example that includes some of the terms you’ll be needing to use and understand.

John watches his grandmother bake bread. He ask his grandmother what makes the bread rise. She explains that yeast releases a gas as it feeds on sugar.

John wonders if the amount of sugar used in the recipe will affect the size of the bread loaf?

John researches the areas of baking and fermentation and tries to come up with a way to test his question. He keeps all of his information on this topic in a journal.

After talking with his teacher and conducting further research, he comes up with a hypothesis. “If more sugar is added, then the bread will rise higher.”

Do you know the difference between the independent and dependent variables?

The independent, or manipulated variable, is a factor that’s intentionally varied by the experimenter. John is going to use 25g., 50g., 100g., 250g., 500g. of sugar in his experiment.

The dependent, or responding variable, is the factor that may change as a result of changes made in the independent variable. In this case, it would be the size of the loaf of bread.

His teacher helps him come up with a procedure and list of needed materials. She discusses with John how to determine the control group.

Because his grandmother always used 50g. of sugar in her recipe, John is going to use that amount in his control group.

John’s teacher reminds him to keep all other factors the same so that any observed changes in the bread can be attributed to the variation in the amount of sugar. These factors are called constants

Can you think of some constants for this experiment?

Other ingredients Type of oven Rising time Brands of ingredients Cooking time Type of pan used Oven temperature Age of yeast ETC…

John writes out his procedure along with a materials list in his journal.

Trials refer to replicate groups that are exposed to the same conditions in an experiment. John is going to test each sugar variable 3 times.

John gets all his materials together and carries out his experiment.

Amt. of Sugar (g.) 123Average Size (cm 3 ) Size of Bread Loaf (cm 3 ) Trials Control group

John examines his data and notices that his control worked the best in this experiment, but not significantly better than 100g. of sugar.

John rejects his hypothesis, but decides to re-test using sugar amounts between 50g. and 100g.

Once again, John gathers his materials and carries out his experiment. Here are the results.

Amt. of Sugar (g.) 123Average Size (cm 3 ) Size of Bread Loaf (cm 3 ) Trials Control group

John finds that 70g. of sugar produces the largest loaf. His hypothesis is accepted.

Ms. Webb wants to know if a new brand of sneakers can help our cheerleaders jump higher as they cheer on the Eagles. She gave out new Nikes, Adidas, or Reeboks to most of the girls and the rest of the squad wore the old, non-name brand sneakers. Then she measured each girl’s jump height and took the average for each shoe type. Shoe TypeAverage Jump Height Nike10 inches Adidas7 inches Reeboks7 inches Non-name brand5 inches Practice Problem #1

A study was designed to determine if a chemical called antirosa prevents conjunctivitis (pink eye). 10,000 individuals were divided into four groups. Each person took a pink pill every morning for one year. Some patients received 3 grams of antirosa, some received 6 grams of antirosa, some received 9g of antirosa and some received a sugar pill. Then the number of times patients developed conjunctivitis was measured

A scientist conducted an experiment to test whether maple seeds exposed to acid rain will take longer to grow than seeds exposed to normal rain. The scientist set up four groups. The water used for each group had a different pH value: 5.6, 4.0, 3.0, and 2.0. Normal rain has a pH of 5.6 and acid rain has a pH between 1.5 and 5.0. After ten days, the number of seeds that had germinated (grown) in each group was counted.