Scientific Procedure and Lab Safety

Test next Friday/Monday on:1. Lab Safety; steps and reading labels2. Identifying a problem, writing a hypothesis,

writing a conclusion3. Data – quantitive and qualitative; inference

versus observation4. Independent variable, dependent variable,

constant, control, repeated trials5. Metric conversions

Lab Safety

• Never work alone in the lab• Leave all backpacks, etc. in the classroom• Do not pull out chairs and sit down• No food or drink• Read all label and make sure you know what

materials are in each of the containers at your table. They should be labeled.

• Proper dress

Important Terms

• Flammable – how easily something will burn or ignite

• Disposal – method of getting rid of waste. Substances should not be put down the sink or thrown in the trash unless the teacher gives permission.

• Combustible – how easily something will explode• Toxic – the degree to which a substance can

damage a person or other organism.

What are SI units?

International system of units used by the scientific community. It includes:meter for lengthkilogram for masssecond for timeampere for electric currentkelvin for temperaturecandela for luminous intensitymole for the amount of substance.

SI Conversions

• SI units are in tens.

Complete the worksheet and thenon the back write down some examples

of what you would use each of these units to measure.

What factors are Kept constant in this experiment?

Constant

Things that are kept the same in an experiment.

What factors are Can you control in this experiment?

Independent Variable

An independent variable is the variable you have control over. It’s what you can choose and manipulate. It is usually what you think will affect the dependent variable.

Goes on the X axis

What factors is the result of the experiment that will make up your data?

Dependent Variable (Results)

The dependent variable responds to the independent variable. It is called dependent because it "depends" on the independent variable.

Goes on the Y axis

Variables and Controls

Example #1Ms. S. decides to test if flicking kids with rubber bands will get them to stop talking. She splits the class in half and flicks the half on the left every time they talk. She does not flick the kids on the right when they talk. Independent Variable:Dependent Variable:Control:Measurement:Constants:

Control

Sometimes an experiment needs a basis for comparison – something you are NOT experimenting with.

Variables and Controls

Example #1Ms. S. decides to test if flicking kids with rubber bands will get them to stop talking. She splits the class in half and flicks the half on the left every time they talk. She does not flick the kids on the right when they talk. Independent Variable:Dependent Variable:Control:Measurement:Constants:

What could you add to this experiment that would be a control?

Variables and Controls

Example #2Katie wants her pumpkins to grow faster so she puts cow manure on 3 of her plants, chicken manure on 3, and humanure on 3. Independent Variable:Dependent Variable:Control:Constants:

Measurements

Katie’s Data:Plant 1: .517 cmPlant 2: .00529 mPlant 3: .204 in

If all plants were the same height at the beginning, which plant grew the most?

What are some constants in this experiment?

Quantitative data vs. Qualitative data

Qualitative – data or observations that are obtained through the five senses.Quantitative data – data that is collected as a result of scientific measurement usually with tools like a ruler, balance, graduated cylinder, etc.

Inference vs. Observation

• Inference – a conclusion drawn from an observation

• Observation – either quantitative or qualitative. These are limited to what you can measure or gather from your senses.