Lab Skills and Safety Demonstrations

See also: Measurement and Units

Lab skills and safety demonstrations teach essential techniques and practices for working responsibly in a laboratory. They are foundational because mastering safety and basic skills ensures that all other experiments can be carried out successfully.

Demonstration	Materials	Difficulty	Safety	Summary
Buchner Filtration	★★☆	★★☆	★★☆	Use a Buchner funnel and side-arm vacuum flask to separate a solid from a liquid quickly. The slurry is pulled through wetted filter paper by reduced pressure, leaving the solid on the paper for washing and drying.
Bunsen Burner Operation	★★☆	★☆☆	★☆☆	This demonstration outlines the safe and correct use of a Bunsen burner, including preparation, lighting, use, and shutdown.
Bunsen Burner Soot	★★☆	★☆☆	★★☆	This demonstration shows how a Bunsen burner flame changes with oxygen supply. With the air hole closed, the yellow flame results in incomplete combustion, producing soot that can be collected on a cool object. Opening the air hole provides more oxygen, producing a blue flame from complete combustion.
Cylinder Puzzle Model of Scientific Inquiry	★☆☆	★☆☆	★☆☆	The cylinder puzzle is a hands-on activity to model how scientists work. Students investigate an opaque cylinder threaded with ropes. By pulling on different knots and observing the results, they form and test hypotheses about what is hidden inside. The puzzle highlights observation, explanation, prediction, and the limits of scientific certainty.
Dart Drop Accuracy, Precision, and Uncertainty	★★☆	★☆☆	★★☆	Students drop different darts onto a target from varying heights and by different droppers, then analyze how accuracy (closeness to the center), precision (clustering), and uncertainty (spread/standard deviation) change with those variables.
DIY Centrifuge	★☆☆	★☆☆	★★☆	Centrifuges can be built using a variety of low cost methods. These range from hand-powered “paperfuge” whirligigs to salad-spinner and Dremel-driven rotors.
Edible Candle	★☆☆	★☆☆	★★☆	In this fun demonstration, a peeled potato shaped like a candle and topped with a burning almond slice looks just like a real candle.
Extrapolation and Interpolation With Spaghetti	★★☆	★☆☆	★☆☆	Students measure the mass and length of broken pieces of dry spaghetti, plot the data on a graph, and use a line of best fit to predict the mass of unmeasured lengths. This activity introduces the use of graphs for making predictions and demonstrates proportional relationships between variables.
Gravity Filtration	★★☆	★☆☆	★☆☆	Gravity filtration is a laboratory method used to separate a solid residue from a liquid filtrate by passing the mixture through filter paper held in a funnel. The technique allows suspended solids to be collected while the clear liquid passes through.
Investigating Plant Growth	★☆☆	★☆☆	★☆☆	Students set up several seedling pots to test one need at a time by comparing a control with three treatments: no water, salt water, and no light. They track growth over time using simple height markings to decide which conditions help plants stay healthy.
Limewater Test for Carbon Dioxide	★★☆	★☆☆	★☆☆	Carbon dioxide can be detected by bubbling the gas through limewater, which is a solution of calcium hydroxide. If carbon dioxide is present, the limewater turns milky or cloudy white due to the formation of calcium carbonate.
Pieces of the Story	★☆☆	★★☆	★☆☆	In this classroom activity, students each receive a random page from a cut-up book. They share the characters, ideas, and places from their page, and then the class works together to create a possible storyline. The demonstration illustrates how science often works with incomplete data to build larger explanations.
Teaching Hand Washing with UV Light	★★★	★☆☆	★☆☆	Students apply a special hand wash training lotion that glows under UV light, then wash their hands. Areas that were not washed thoroughly will still glow, providing a visual demonstration of the importance of using soap and washing all parts of the hands.
Thermal Decomposition of Ammonium Chloride	★★☆	★☆☆	★★☆	Ammonium chloride, when heated, undergoes decomposition into hydrogen chloride and ammonia gasses, before reforming when cool. The process appears similar to sublimation and deposition.
Use of Laboratory Balances	★★☆	★★☆	★☆☆	This demonstration explains the correct use of analytical and top-loading balances in the laboratory. It covers accuracy requirements, weighing techniques, and best practices to ensure precise and reliable mass measurements.
Use of Volumetric Pipette	★★☆	★★☆	★☆☆	Correct technique for using a glass volumetric pipette.
Using a Burette	★★☆	★☆☆	★☆☆	A buret is a precise laboratory instrument used to deliver measured volumes of liquid. By reading the initial and final liquid levels, the exact volume dispensed can be calculated to a high degree of accuracy.
Using a Measuring Cylinder	★★☆	★☆☆	★☆☆	This demonstration shows how to correctly measure the volume of a liquid using a measuring cylinder, a common piece of laboratory equipment.
Using a Separating Funnel	★★☆	★★☆	★★☆	Students learn how a separating (separatory) funnel is used to separate immiscible liquids by density and solubility differences. The demonstration covers correct setup, safe shaking and venting, identifying layers, draining/pouring layers, troubleshooting emulsions, and drying an organic layer.
Using Volumetric Flasks	★★☆	★★☆	★☆☆	Volumetric flasks are precision glassware designed for preparing exact solution volumes, most often used for making dilutions and standard solutions. They allow accurate adjustment of a liquid to a single graduation mark, ensuring reliable concentrations for laboratory testing.
Wafting Demonstration with Ammonia	★★☆	★☆☆	★☆☆	This demonstration shows why it is important to waft chemical vapors instead of smelling them directly. Ammonia vapor rising from an ammonium hydroxide solution is detected by phenolphthalein-treated paper, which turns pink in the presence of the base.
Wet Mount Microscope Slide	★★☆	★☆☆	★☆☆	A wet mount slide allows you to observe living cells or microorganisms in a drop of liquid under a microscope. It is a simple and quick method, but requires careful handling to avoid air bubbles and excess liquid.

Materials
★☆☆ Easy to get from supermarket or hardware store
★★☆ Available in most school laboratories or specialist stores
★★★ Requires materials not commonly found in school laboratories

Difficulty
★☆☆ Can be easily done by most teenagers
★★☆ Available in most school laboratories or specialist stores
★★★ Requires a more experienced teacher

Safety
★☆☆ Minimal safety procedures required
★★☆ Some safety precautions required to perform safely
★★★ Only to be attempted with adequate safety procedures and trained staff