Scientific Method & Lab Safety (Sect. 1.2, pp. 11-18)Mrs. Geist, BiologySwansboro High School, 2010-2011

Warm-Up

What do you already know about the scientific method? Can you identify any stages?

In your opinion and past experience, what are some precautions that we should take in the laboratory?

Standards & ObjectivesNC SCOS 1.02: Design and conduct scientific

investigations to answer biological questions.SCOS 1.04: Apply safety procedures in the

laboratory and in field studies.Objectives: - Take safety precautions in the

lab. What are the steps of the scientific method? What is the difference between an independent

variable and a dependent variable? Why is it important to have a control group in

an experiment?

Lab Safety Contract Highlights

General Rules Highlights

#1 , 2, & 6- Follow your teacher’s directions carefully and conduct yourself responsibly.

#4 &8- Do not touch any equipment, chemicals, or materials unless your teacher instructs you to do so and no fooling around in the lab.

#7 & #15- Read procedures and labels carefully and thoroughly.

#9 & 10- Keep work areas and aisles clean and tidy. Backpacks under the desks.

#13- Be alert and use caution.

General Rules Highlights (cont’d.)

#11- Know the locations and operations procedures of all safety equipment: First aid kit Eyewash station Fire extinguisher, etc.

#14- Dispose of all chemical waste properly. ONLY water down the sink.

#16- Keep hands away from face, eyes, mouth, and body while using chemicals. After experiments, wash your hands thoroughly.

General Rules Highlights (cont’d.)

#19- Know fire drill procedures.#21- When carrying knives and sharp objects,

keep the point down and away.#22- Let your teacher know of any medical

conditions to ensure your safety (e.g., allergies, pregnancy, etc.).

Clothing Highlights

#23- Wear safety glasses/goggles when using chemicals, heat, or glassware. NO EXCEPTIONS!

#24- Contact lens wearers must wear goggles. Please notify your teacher.

#25- Tie back long hair. Secure dangling jewelry and loose/baggy clothing. No open-toed/open-heeled shoes.

#26- Lab aprons should be worn if provided.

Accidents & Injuries Highlights

#27 & 28- Report any accident or injury immediately to teacher, no matter how trivial it may seem.

#29- If a chemical splashes in your eye(s), immediately flush with running water from eyewash stations for at least 20 min. and notify teacher immediately.

Chemicals Highlights#31- All chemicals are to be considered

dangerous. DO NOT touch, taste, or smell any chemicals unless told to do so.

#32, 38, & 39- Check the label on chemical bottles twice. Take only as much chemical as you need and never remove it from the lab. Hold securely and walk carefully when moving chemicals in the lab.

#35- When transferring reagents, hold the containers away from your body.

#36- Use extreme caution when working with acids. “Add acids to water ‘cause you oughta.”

Glassware & Equipment Highlights

#41- Never handle broken glass with bare hands. Use a brush and dustpan.

#44- When removing an electrical plug, grasp the plug NOT the cord.

#45- Never use chipped, cracked, or dirty glassware.

#46- Report damaged equipment immediately.#47- Do not put hot glassware in cold water as it

may shatter.

Heating Substances Highlights

#51 & 53- You will be instructed in the proper method of heating and boiling liquids in test tubes. NEVER point the open end at yourself or anyone else.

#52- Use tongs or heat-protective gloves if necessary.

#53- Never place a hot apparatus on the lab desk. Use an insulating pad.

Lab Safety Contract

You and your parent must read and sign the lab safety contract prior to your participation in any labs.

Scientific Method

Scientific MethodScientific Method: the common steps that

scientists use to gather information and answer questions.

No fixed stepsMost commonly includes:

Identifying a problem Forming a hypothesis Developing and running an experiment Making observations and recording data Analyzing data and drawing conclusions

Observing & Hypothesizing

Identifying a problem: The school needs to decide whether to hire Pepsi or Coca-Cola as the vendor to supply the drink machines.

Observation: Mrs. Andre notices a number of students with Pepsi cans at lunch.

Hypothesis: educated guess. Written as an “If…, then…” statement. If we run a blind test of Pepsi vs. Coke, then

more people will prefer Pepsi.

ExperimentingExperiment: investigation that tests a

hypothesis by collecting data and using controls

Control: receives no experimental treatment; serves as a basis for comparison. Ex: use the same kind of cups, same amount of

beverage, same temperature

Experimenting

Independent Variable: In a controlled experiment, only 1 condition is changed at a time. ex: type of soda Graphed along x-axis (horizontal)

Dependent Variable: Changes that occur as a result of a change in the independent variable. Ex: satisfaction rating, beverage preference Graphed along y-axis (vertical)

Collecting data

Data: information gathered from an experiment. Ex: tally the number of people that preferred Coke

and the number that preferred Pepsi Quantitative (numerical) data: deals with numbers

and measurements Ex: measurements of time, mass, area, volume, etc;

counts Qualitative data: descriptions. Observed not

measured. Ex: color, taste, smell, appearance, beauty

Reporting & Analyzing Data

Data may be expressed in many forms: verbal (written), graphical, tables

Was the hypothesis supported/not supported by the data?

Are more data needed?Compare results and conclusions with that of

published studies. Other scientists verify results by repeating

procedure.

Theories & LawsWhen 1+ hypotheses are verified repeatedly,

they become a theory. Explanation of a set of related observations or

events.Law- description of natural phenomena.

holds true under specific conditions and will occur under certain circumstances.

A law describes a single action, whereas a theory explains an entire group of related phenomena (much more complex).