LAB TechniquesMeasurement, Tools, Skills

aka: what you’ll be doing in the lab ALL year long

Measurement

• In science, we use the metric system. – Don’t Forget! “Inches” is a swear word. Don’t

use it in this classroom.

• We will use measurements to find the mass, volume, and length of various objects.

Length Measurement• To measure length, we will typically use a

ruler.

• We measure in centimeters.

• It’s actually a good idea to not measure at “0”

Volume Measurement

• To measure the volume of something solid:– L x W x H– measure in “cm”– volume units are cm3

Volume Measurement

• A commonly used instrument to measure liquid volume is the graduated cylinder. 

• We measure the liquid volume in milliliters (ml).  

Mass Measurement

• The triple beam balance is commonly used to measure mass in the biology lab.

• Masses on a triple-beam balance can be measured in grams.

Lab Tools We Will Be Using

• Some tools you’ll need to familiarize yourself with:– Microscopes– Paper Chromatography– Gel Electrophoresis

Microscopes

• We will be observing several objects that are difficult or impossible to see with the naked eye.

• Microscopes provide magnification into the world of smaller organisms.

• Two microscopes we will use in the lab:– Compound light microscope– Dissecting microscope

Chromatography• Paper chromatography is a

procedure used to separate substances in a mixture.

• Typically, the substances that are moved are pigments.

• This process occurs because of capillary action.

Gel Electrophoresis

• Gel electrophoresis is a procedure used to separate charged molecules of different sizes by passing them through a gel in an electrical field. 

• We use this process to compare DNA strains.

• The DNA is cut by enzymes, then moved through the gel according to size.

Laboratory Skills

• When you’re in the lab, besides using tools, you’ll also need to practice appropriate skills. This year, we will focus on using and understanding:– Indicators– Dichotomous Keys– Dissection Techniques

Indicators

• Indicators are substances which are used to provide information about the classification of a particular substance. 

• Some commonly used indicators in the living environment/biology lab include:– Litmus (pH) paper– Lugol's (iodine) solution – Benedict's solution. 

Dichotomous Keys

• Making sense of observations is important in science. Classification provides a means of describing objects or organisms by their common characteristics. 

very BASIC example

Dichotomous Keys

• A dichotomous key is used to provide a method of sorting categories of organisms and specifically identifying particular organisms.

Dissection Techniques

• The dissection of representative plant and animal specimens is a required skill for the living environment/biology course. 

• Dissection provides information about the internal and external characteristics of a specimen in a direct manner which other techniques can not directly provide. 

Dissection Techniques

• Specimens we’ll be looking at include:– Flowers– Frogs– Fetal Pigs