Introduction to Biology
Senior 1 · Biology
Introduction to Biology
Lesson 3 of 4
20 min
During a practical lesson in a school in Huye, Eric heats water in a test tube to see what happens to a leaf. He holds the tube upright with his fingers and points the open end at his partner Aline. The water boils suddenly and hot drops land on her arm. Meanwhile, at the next bench, a student is eating a mandazi beside a dish of iodine solution, and a school bag lies in the walkway between the benches.
No one meant to cause harm. Every one of these problems is prevented by a simple rule. This lesson gives you those rules and, more importantly, the reason for each one.
Definition
Laboratory: a room equipped for scientific experiments and investigations.
Hazard: anything that could cause harm, such as a flame, broken glass or a corrosive chemical. Risk is how likely it is that the harm actually happens.
Hazard symbol: a picture on a container that warns what kind of danger its contents carry (Figure 1).
Personal protective equipment (PPE): clothing and equipment that protect the user, such as a lab coat, safety goggles and gloves.
Look at the bottles on the shelves of your school laboratory. Many carry a red diamond with a black picture. Before you open any bottle, find its symbol and read the label.
Figure 1: Four hazard symbols you will find on bottles in a school laboratory (simplified drawings of the international symbols).
| When | Rule | Reason |
|---|---|---|
| Before you start | Enter the laboratory only when a teacher is present. | Someone trained must be there to prevent and deal with accidents. |
| Know where the exits, fire extinguisher, fire blanket and first aid kit are. | In an emergency there is no time to search. | |
| Read the instructions fully before you touch anything. | Most accidents happen when steps are done in the wrong order. | |
| During the work | Wear a lab coat and eye protection; tie back long hair; wear closed shoes. | Protects skin, eyes and feet from spills, splashes and broken glass; keeps hair out of flames. |
| Never eat, drink or taste anything in the laboratory. | Food can pick up chemicals or microorganisms from the bench. | |
| Smell a substance only by wafting it towards your nose with your hand. | Breathing in a gas directly can damage your nose and lungs. | |
| Point the open end of a heated test tube away from everyone (Figure 2). | Liquids can boil suddenly and shoot out. | |
| Label every container; never put unused chemicals back in the stock bottle. | Unlabelled or contaminated chemicals cause dangerous mistakes later. | |
| Report every spill, breakage or cut to the teacher at once. | Small accidents become serious ones if they are hidden. | |
| When you finish | Put broken glass in the container for broken glass, never in the ordinary bin. | Cleaners can be cut by glass they cannot see. |
| Turn off gas, water and electricity; clean the bench. | Leaves the room safe for the next class. | |
| Wash your hands with soap and water. | Removes chemicals and microorganisms before you eat or touch your face. |
Heating is where most school laboratory injuries happen, so learn this set-up well.
Figure 2: The safe way to heat a liquid in a test tube. Keep moving the tube gently in the flame so the liquid does not boil suddenly and shoot out.
Warning
Two common mistakes. (1) Looking straight down into a test tube while heating it: if it spurts, the liquid goes into your eyes. Look from the side. (2) Picking up a hot tube or tripod because it "looks cool": hot glass and metal look exactly like cold glass and metal. Use tongs or a holder and let things cool.
Worked example 1: spot the broken rules
Use the story at the start of this lesson. List each unsafe act and the rule it breaks.
Answer: four rules were broken; pointing the tube away from everyone would have saved Aline's arm (the holder protects the fingers of the person heating).
Worked example 2: a spill on the skin
Dilute acid splashes on to the back of Keza's hand. What should happen, in order?
Reason: water is the first response to almost every chemical splash on skin or in the eyes, because it removes the chemical quickly.
The same rules protect people in hospital laboratories, at the national reference laboratory of the Rwanda Biomedical Centre, in factories and in agricultural research stations. Health workers wear gloves and coats, label every blood sample, and separate waste into general waste, infectious waste and sharps (needles and broken glass) so that cleaners and the public are not harmed. The habits you practise in the school laboratory are the habits of every professional scientist.
Health and Safety Essentials: Laboratory Best Practices (Royal Society of Chemistry). Watch for what the scientists wear and how they keep their benches organised.
Tip
Memory hook: before any practical, ask three questions: What could hurt me? What could hurt others? What will I do if it goes wrong?
Practice: laboratory safety
Key points
Sources and credits
Written by Ganzaa: the lesson text, Figures 1 and 2, the table, the worked examples and the practice questions. The hazard symbols are simplified drawings of the Globally Harmonized System (GHS) pictograms.
