Science on This Day: November 19 | Conservation of Matter, Molecular Reactions and Apollo 12
November 19 brings together three stories that show science working at very different scales. Mikhail Lomonosov explored ideas about matter and the physical world, Yuan Tseh Lee helped scientists investigate what happens when molecules collide, and Apollo 12 demonstrated how engineering and scientific investigation could work together on the Moon.
These events make useful classroom starting points because they connect familiar ideas, such as chemical reactions and the conservation of matter, with research at the molecular scale and exploration beyond Earth. Each also offers an opportunity to move students beyond memorising facts and towards asking how scientists gather evidence and test explanations.
Mikhail Lomonosov: understanding matter and its transformations
On November 19, 1711, Russian scientist Mikhail Vasilyevich Lomonosov was born. His work crossed several fields, including chemistry, physics and astronomy. He was interested in how the natural world worked and contributed to early arguments about the conservation of matter.
The principle of conservation of matter is central to chemistry today. In an ordinary chemical reaction, atoms are rearranged into new combinations, but they are not created or destroyed. If we account for all the reactants and products in a closed system, the total mass remains the same.
This idea can sound straightforward, but it has important consequences for how students learn to explain chemical reactions. When a substance burns, rusts, dissolves or reacts with another chemical, it may look very different afterwards. Gases can escape, solids can form, and colours can change. These visible changes can make it seem as though matter has appeared or disappeared.
For example, when a candle burns, the wax reacts with oxygen in the air. The products include gases such as carbon dioxide and water vapour, which disperse into the surroundings. If students only measure the candle before and after burning, they may conclude that matter has been lost. Measuring the entire system, including the oxygen consumed and the gases produced, gives a more complete picture.
Lomonosov's work provides a historical connection to the development of ideas about matter, but the principle is best taught through evidence. Students should see how measurements and explanations can help resolve apparent contradictions between what they observe and what is happening at the particle level.
A classroom connection: where does the mass go?
Ask students what they think happens to mass when a chemical reaction produces a gas. Before carrying out an experiment, have them make a prediction and explain their reasoning.
A suitable demonstration is a reaction that produces gas inside a sealed system, using an appropriate classroom-safe setup. Students can compare the mass of the complete system before and after the reaction. If the system remains sealed and the balance is suitable, the total mass should remain essentially unchanged, even though the substances inside have changed.
Safety matters: the container must be suitable for the reaction and must not be sealed in a way that creates a dangerous pressure build-up. Teachers should choose a safe, low-pressure demonstration and follow the relevant laboratory guidance.
Students can then compare this with a reaction carried out in an open container. If gas escapes, the measured mass of the remaining material may decrease. The matter has not vanished; some of it has left the system being measured.
This makes a useful lesson about both chemistry and experimental design. What counts as the system? What is being measured? Which substances might not be included in the measurement? These questions help students understand why a scientific explanation depends on collecting the right evidence.
For further classroom-ready activities across science topics, explore The Teaching Astrophysicist’s resource store, which includes free and paid materials.
Yuan Tseh Lee: watching chemical reactions at the molecular scale
On November 19, 1936, chemist Yuan Tseh Lee was born. Lee became known for his work studying chemical reactions using crossed molecular beams. He shared the 1986 Nobel Prize in Chemistry with Dudley R. Herschbach and John C. Polanyi for contributions concerning the dynamics of chemical elementary processes.
Chemical reactions happen when particles interact and their atoms are rearranged. At the scale of individual molecules, however, a reaction is not simply a matter of putting two substances together and waiting for a product. The direction, speed and energy of colliding particles can affect what happens when they meet.
Lee's research helped scientists investigate these interactions more directly. In crossed molecular beam experiments, beams of particles travel through a highly controlled environment and collide. By studying the products and how they move after a collision, researchers can learn about the mechanisms of chemical reactions.
This research is important because the overall equation for a reaction does not necessarily tell us every step that occurs. A balanced equation identifies the reactants and products, but it may not show the sequence of molecular interactions that produces them.
Understanding those details can help scientists explain why reactions happen at different rates or produce different outcomes under different conditions.
The work also illustrates the value of controlling variables. If scientists want to understand how particles interact, they need to limit interference from other particles and measure the collision conditions as carefully as possible. Experiments at this scale require sophisticated equipment, but the underlying question is familiar to students: how can we tell what causes a particular result?
A classroom connection: what affects a reaction?
Students can investigate reaction rates using accessible experiments, such as observing how temperature affects the rate at which an appropriate effervescent tablet reacts in water. They can measure the time taken for a defined change to occur, while keeping other factors as consistent as possible.
The experiment does not reproduce molecular beam research, and students should not assume that a large-scale reaction-rate test reveals every detail of a reaction mechanism.
Instead, it introduces a shared scientific principle: controlling conditions helps us understand how particles behave.
Ask students to identify the independent variable, the dependent variable and the factors that should be controlled. They can then consider why a fair test matters and what additional equipment or measurements would be needed to investigate collisions between individual molecules.
For older students, this can lead to a discussion of collision theory. Particles need to interact in suitable ways for a reaction to occur, and the energy of those interactions matters. Students can compare this model with evidence from reaction-rate experiments and consider what the model explains well, as well as what it leaves out.
Lee's work provides a bridge between classroom chemistry and modern research. It shows how scientists can investigate the mechanisms behind familiar reactions rather than stopping at the observation that a reaction has occurred.
You can read more about Lee’s research through the Nobel Prize’s account of the 1986 Chemistry Prize.
Apollo 12 lands on the Moon: science and engineering working together
On November 19, 1969, Apollo 12 made the second crewed lunar landing. Astronauts Charles “Pete” Conrad and Alan Bean landed the Lunar Module near Surveyor 3, a robotic spacecraft that had reached the Moon in 1967. The crew later retrieved parts of Surveyor 3, including its television camera, for examination back on Earth.
This was more than a demonstration of accurate lunar navigation. Surveyor 3 had spent more than two years exposed to the lunar environment. Scientists could examine its returned components to investigate how materials and equipment had changed after prolonged exposure to vacuum, temperature extremes, radiation and lunar dust.
The mission provides an example of how exploration can create opportunities for experiments that would be difficult to conduct on Earth. Materials behave differently depending on their environment, and equipment designed for space must cope with conditions that are rare or absent at the surface of our planet.
It also demonstrates how robotic and crewed missions can complement one another. Surveyor 3 gathered information before astronauts arrived. Apollo 12 then allowed people to examine the spacecraft directly and return selected parts for further analysis. The two missions contributed different kinds of evidence.
Apollo 12 also required careful engineering and navigation. Its landing near Surveyor 3 was planned so that astronauts could reach the earlier spacecraft. Getting close enough to retrieve parts required an accurate landing, a suitable route across the lunar surface and coordination between the crew and mission control.
A classroom connection: what changes when materials go to space?
Ask students to choose a material or piece of equipment that might be used on the Moon.
What conditions would it need to withstand? They might consider temperature changes, radiation, vacuum, dust, impacts or repeated movement.
Students can design a simple investigation that models one aspect of material performance under safe classroom conditions. For example, they could compare how different materials respond to heating and cooling, or investigate which surfaces are easiest to clean after exposure to a dust-like material. These activities are models, not complete simulations of the lunar environment, so students should explain what their investigation can and cannot tell them.
A useful extension is to ask why scientists would bring a component back to Earth instead of studying it only on the Moon. Students can compare direct observation, measurements made by instruments and laboratory analysis of returned samples. Each method provides different evidence and has its own limitations.
Apollo 12 is an engaging case study for space science, engineering and materials science because it shows how one mission can build on the results of an earlier mission. NASA’s Apollo 12 mission page provides additional background for classroom discussion.
Bringing the three stories together
At first glance, conservation of matter, molecular collisions and lunar exploration may seem like unrelated topics. However, all three depend on making careful observations and building explanations from evidence.
Lomonosov's work connects to the question of how scientists account for matter during physical and chemical changes. Lee's research examines what happens during interactions between molecules. Apollo 12 shows how instruments, materials and samples can be used to investigate conditions beyond Earth.
For a short classroom activity, ask students to choose one of the three events and answer three questions: What scientific question were researchers trying to address? What evidence could help answer it? What are the limitations of that evidence? Students can share their responses and compare how scientific methods differ between chemistry research and space exploration.
This approach helps students see science as a process rather than simply a collection of discoveries. Scientific knowledge grows when people make measurements, test explanations, develop better tools and revisit questions with new evidence.
Use Science on This Day as a classroom resource
Science history works well as a lesson starter because it gives students a concrete story before introducing a scientific concept. A short reading about Apollo 12 can lead into a lesson on engineering design, while Lomonosov's work can introduce conservation of matter and Lee's research can provide a starting point for reaction rates and collision theory.
The November Science on This Day resource set contains 109 STEM stories across the 30 days of November. It includes an interactive HTML version with filters and classroom display features, editable slides with discussion questions, a filterable spreadsheet and a PDF version. Teachers can select a story to fit the topic they are teaching, whether they need a quick discussion prompt, a reading activity or an introduction to a larger unit.
You can also browse The Teaching Astrophysicist’s store for other free and paid resources across science disciplines.
Looking ahead: more science history in November
November 20 brings the birth of astronomer Edwin Hubble in 1889. His observations helped establish that galaxies exist beyond the Milky Way and contributed to evidence that the universe is expanding. This offers a natural connection to galaxies, the scale of the universe and how astronomers use observations to investigate distant objects.
Later dates in November feature more stories from astronomy, physics, chemistry, biology, engineering and computing. Each can be used to introduce a new concept, revisit an earlier topic or ask students to connect classroom science to real investigations.
The most effective science-history activities do more than ask students to remember who did what and when. They encourage students to consider how knowledge was developed, which evidence mattered and what questions remain. November 19 provides three different routes into that discussion, from the behaviour of matter to molecular collisions and the challenges of exploring another world.
Thanks for reading
Cheers and stay curious
Oliver - The Teaching Astrophysicist
