Measurement and Units Demonstrations

See also: Chemical Quantities and Calculations, Lab Skills and Safety

Measurement and units demonstrations show how scientists quantify observations using standard systems. They are essential because consistent measurement underpins all of science, and clear demonstrations help students see why accuracy and units matter.

Demonstration	Materials	Difficulty	Safety	Summary
Burning Steel Wool Increases Its Mass	★★☆	★★☆	★★☆	When steel wool is ignited, it reacts with oxygen in the air to form iron oxide. Surprisingly, the mass of the steel wool increases after burning because oxygen atoms from the air combine with the iron atoms.
Measure the Earth	★★☆	★★☆	★☆☆	Using a stick, a measuring tape, and basic geometry, students can replicate Eratosthenes’ ancient experiment to measure the size of the Earth. By measuring the length of a stick’s shadow during the equinox, they calculate Earth’s circumference with surprising accuracy.
Conservation of Mass with Baking Soda and Vinegar	★★☆	★☆☆	★☆☆	This experiment shows that matter is not created or destroyed in a chemical reaction. When baking soda reacts with vinegar, carbon dioxide gas inflates a balloon, and the total mass before and after the reaction remains nearly the same.
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.
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.
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.
Scale Model of the Solar System	★☆☆	★☆☆	★☆☆	Students calculate and build a scale model of the solar system using beads, string, chalk, or yard markers to represent planet distances, sizes, or both. The activity demonstrates the vast differences in planetary distances and diameters, helping students grasp the scale of our solar system.
Measuring the Speed of Sound with a Drum	★★☆	★☆☆	★☆☆	One student beats a drum at a steady rate while others back away until the strike is seen at the same instant the previous beat is heard. Using the beat period and the measured distance at that point, students estimate the speed of sound.
Use of Volumetric Pipette	★★☆	★★☆	★☆☆	Correct technique for using a glass volumetric pipette.
Limiting Reactant	★☆☆	★★☆	★☆☆	Balloons filled with different amounts of baking soda are attached to flasks containing vinegar, producing varying amounts of carbon dioxide gas.
Performing a Titration	★★☆	★☆☆	★☆☆	A standard solution in a buret is added to an unknown solution in a flask until the reaction reaches its endpoint, signaled by an indicator color change (or pH jump). Initial and final buret readings are used to calculate the unknown molarity.
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.

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