Topic: Scientific Method Aim: Explain how a controlled experiment is performed. Do Now: 1. Take out your lab safety activity. 2. Tape the Experimental Variables reading on the first piece of paper in your ISA section. Write the answers on the loose- leaf below. HW: Complete Part 2 of Lab Safety Activity.

Let’s summarize… Identify the improper lab procedure observed in the diagram.

Let’s review…Identify the improper lab procedure observed in the diagram.

Identify the ONE factor that is difference between all three flower pots. Amount of water

The ONE factor between all set- ups that is DIFFERENT Variable

Does fertilizer X help plant growth?

Group AGroup B

Identify the variable in this experiment. Experimental Group Control Group

2 groups: 1.Experimental group: has the VARIABLE 2.Control group: DOES NOT have the variable Parts of a controlled experiment

Control Group Experimental Group Group A Group B Explain why group B is the experimental group.

1.Independent Variable: the 1 factor that is DIFFERENT between groups 2 types of variable s

Independent variable = ? SUNLIGHT

2. Dependent Variable = what is MEASURED (data) HEIGHT

Topic: Scientific Method Aim: Explain how a controlled experiment is performed. Do Now: 1. Take out your lab safety activity. 2. Make sure your 3 binder sections are set up: Class Notes, ISA, Homework HW: Finish Lab Safety Activity.

Let’s summarize… Identify the improper lab procedure observed in the diagram.

Height = 21 cm Height = 12 cm

1. Identify the independent variable. Amount of water 2. Identify the dependent variable. Width of pedals

Group AGroup B

ONE Everything else must be kept the same  CONTROLS or CONSTANTS How many indep. variables?

Repeat experiment Use a larger sample size To make the results of an experiment more RELIABLE/VALID/RELIABLE

Let’s summarize… 1.Explain the difference between the control and experimental groups. Control group does not have the independent variable. The experimental group DOES HAVE the independent variable. 2. Explain the difference between the independent and dependent variables. The indep. variable is the one factor between set-ups that changes. The dep. variable is what is measured. 3. How can the results of an experiment be more accurate? Repeat the experiment. Use a larger sample size.

Experiment 1.Identify the independent variable. 2.Identify the dependent variable. 3.Explain the difference between the control group and experimental groups in this experiment. Color of light Plant height The group with white light (sunlight) is the control group. Plants under different color lights are the exp. groups.

An investigation was done with an electromagnetic system made from a battery and wire wrapped around a nail. Different sizes of nails were used. The number of paper clips the electromagnet could pick up was measured.

Independent variable: Sizes of nails These were changed by the scientist

Dependent variable: Number of paper clips picked up

Let’s review… Identify the improper lab procedure observed in the diagram.

Let’s summarize… Identify the improper lab procedure observed in the diagram.

The set-up that has the independent variable is known as the a.independent variable b.control group c.dependent variable d.experimental group

What is the factor that changes between all set-ups of an investigation? a.Control b.Independent variable c.Hypothesis d.Dependent variable

During an investigation, what is being measured is called the a.control group b.independent variable c.controls d.dependent variable

What is the factor in an experiment that remains constant or the same? a.Control b.Variable c.Theory d.Hypothesis

The set-up that does not have independent variable is known as the a.independent variable b.control group c.dependent variable d.experimental variable

The results of one experiment carried out by a research team would be considered VALID if a.the experiment had no control setup b.all the members of the research team came to the same conclusion c.the experiment had more than one variable d.the experiment was repeated and the same results were obtained each time

Which statement is true about the experimental group(s) in an experiment? 1.It does not contain the independent variable. 2.It contains 2 variables. 3.It contains the independent variable. 4.It is exactly the same as the control group.

To investigate how temperature affects seed germination, a student placed 10 radish seeds of the same variety on moist paper in each of 3 petri dishes and placed the dishes in the following environments: Dish # 1: Refrigerator, 5ºC Dish # 2: Room Temperature, 20ºC Dish # 3: Incubator, 37ºC 1.Identify the independent variable in this investigation. Temperature

To investigate how temperature affects seed germination, a student placed 10 radish seeds of the same variety on moist paper in each of 3 petri dishes and placed the dishes in the following environments: Dish # 1: Refrigerator, 5ºC Dish # 2: Room Temperature, 20ºC Dish # 3: Incubator, 37ºC 2. Identify the control group. The seeds in room temperature 3. Identify the dependent variable. How many seeds germinated

A student wanted to perform an experiment to test the effect of water temperature on the time it takes an egg to boil. He thinks that the higher the temperature of water, the faster an egg will boil.

Independent variable? temperature of water Dependent variable? time to cook an egg

Beta-carotene supplements have been thought to protect against cancer. A study was conducted with 39,000 women aged 45 and up. Group A received a beta-carotene supplement. Group B received a placebo. Their health was studied over their lifetime. Cancer rates for women taking the beta-carotene supplement did not really differ from the cancer rates of those women taking the placebo.placebo Identify the independent variable, dependent variable, control group, and experimental group.

Independent variable: Beta-carotene supplement Dependent variable: Their health Control group: Group that received the placebo Experimental group: Group that received the supplement

What is the independent variable? Substance Z What is the dependent variable?height Ex # 2: To investigate the effect of a substance on plant growth, 2 bean plants of the same species were grown under identical conditions with Substance Z added to the soil of one of the plants. At the end of 2 weeks, the plant grown with Substance Z was 12.5 cm tall. The plant grown without Substance Z was 12.2cm tall. The researcher concluded that the presence of Substance Z causes the plants to grow taller. Which setup is the control? Plant without Substance Z

What is the independent variable? What is the dependent variable? Which setup is the experimental group? Ex #3: A student placed 5 geranium plants of equal size in 5 environmental chambers. Growing conditions were the same for each plant except for the amount of water each received. At the end of 20 days, the width of the leaves was measured.

5. An investigation was designed to determine the effect of ultraviolet light on mold spore growth. Two groups of mold spores were grown under identical conditions, except one group was exposed only to ultraviolet light, while the other group was grown in total darkness. In this investigation, the group of mold spores grown without receiving any ultraviolet light is known as the a. experimental variable b. hypothesis c. control d. limiting factor