A Boring Lecture - ft. Eggs, Donuts & Pills

Question

You were yawning at your seat, being forced to attend this will-be-boring lecture by an always-boring teacher…

“Good morning class, today, we’ll look into the use of different materials. Well, as we all know, cracking eggshells and doughnuts can make our bones stronger…”

Students nodding… But wait... doughnuts?

“And that pills are used so that bacteria cannot survive.”

By this point (yes, less than one minute after the lecture have started), some of the students were already snoring hard, and the desperate (and “wasted”) professor was (perhaps?) trying to catch the students’ attention…

“But perhaps you may not know that eyeballs were actually used as explosives in modern wars…”

You squinted at the professor, who pulled up a serious face. You were thinking of a punch line for your meme-making project…

“And no one or animals can survive without eggs!”

You thought, Ugh… Another lame pun… He must have meant the egg cell…
Yet the professor seemed to have read your mind, and explained,

“By that I mean… this.”

He used a black marker to draw a crude circle on a piece of white paper and projected it onto the screen.
Mindblown and exhausted, you drifted off now and then, only hearing excerpts of the lecture…

"This lifebuoy is perfect for aircraft components, missiles, spacecraft, and satellites…"

Implant advertising?? You thought…

"And this fabulous aiming device can glow in the dark… belonging to the same series is this ladybug with its cute tummy up, all legs coiling in…"

You rolled your eyes, but you saw an old man in the front row nodding in apprehension…

This lecture is perfectly valid. What kind of a lecture is this, and what is the professor getting at?

Hint 1

They are now often replaced with letters...

Answer 1

This lecture appears to be about:

Chemical elements, using John Dalton's proposed symbols for the elements, which I have pasted below as an image:

cracking eggshells and doughnuts can make our bones stronger…

Calcium, which appears twice, once like a cracked egg (labeled Lime) and once like a doughnut. Of course, calcium makes our bones stronger too.

And that pills are used so that bacteria cannot survive

Nitrogen, which looks like a pill (circle with a line). It also has antibacterial properties according to an internet search.

eyeballs were actually used as explosives in modern wars…

Hydrogen, which looks like an eyeball (circle with dot), and hydrogen bombs are modern explosives.

And no one or animals can survive without eggs

Oxygen, which looks like a circle, and which all animals require to survive.

This lifebuoy is perfect for aircraft components, missiles, spacecraft, and satellites…

Beryllium, which looks just like a lifebuoy, and is used in the named industries.

And this fabulous aiming device can glow in the dark… belonging to the same series is this ladybug with its cute tummy up, all legs coiling in…

Strontium, which looks like the reticle of a gun scope, and which is used in glow-in-the-dark paint. Along with barium, which resembles a belly up ladybug, and which is in the same column as strontium and just underneath it in the periodic table.

Answer 2

Partial answer, but this lecture seems to contain

a lot of visual depictions of the letter O, which perhaps could represent the element oxygen based on the rest of the lecture's content.

Well, as we all know, cracking eggshells and doughnuts can make our bones stronger…

"O" looks like a doughnut. I suspect that "eggshells" and "bones" refer to calcium, but not sure what to do with that information.

And that pills are used so that bacteria cannot survive.

"O" looks kind of like a pill if you stretch it out long enough. Oxygen has also been studied for its anti-microbial properties, which may explain the "bacteria cannot survive" part.

But perhaps you may not know that eyeballs were actually used as explosives in modern wars…

"O" also looks like an eyeball and can be used to cause explosions via combustion.

And no one or animals can survive without eggs!

"O" looks like an egg, and most life on Earth depend on oxygen to survive. And as the professor demonstrated, "O" is a black circle.

This lifebuoy is perfect for aircraft components, missiles, spacecraft, and satellites…

"O" looks like a lifebuoy. All of the listed items contain oxygen in some degree or another, but that doesn't seem specific enough.

And this fabulous aiming device can glow in the dark…

Not sure how this line relates to "O" or oxygen.

belonging to the same series is this ladybug with its cute tummy up, all legs coiling in…

"O" looks like a ladybug viewed from above without its legs.

Answer 3

Partly inspired by PiIsNot3's answer ...

I think the lecture is about chemistry, but the professor is using some odd terminology to refer to the various elements.

cracking eggshells and doughnuts can make our bones stronger

CALCIUM, Ca, 20, and BORON (ref), B, 5.

pills are used so that bacteria cannot survive

COPPER (ref), Cu, 29.

eyeballs were actually used as explosives in modern wars

FLUORINE (ref), F, 9. (I'm not sure about this one. Lots of things used in wars, sadly.)

no one or animals can survive without eggs [crude circle on a piece of white paper]

OXYGEN, O, 8.

lifebuoy is perfect for aircraft components, missiles, spacecraft, and satellites

TITANIUM, Ti, 22.

this fabulous aiming device can glow in the dark

PHOSPHORUS, P, 15. (Quite a few chemical elements glow in the dark - especially radioactive ones - but everything here seems to have a fairly low number on the periodic table, so I'm going for this one.)

ladybug with its cute tummy up, all legs coiling in

No idea about this one.

The main puzzle left to solve is

how do the words "eggshells", "doughnuts", "pills", "eyeballs", "eggs", "lifebuoy", "aiming device", "ladybug" clue the respective chemical elements? Maybe something about the letters contained in the word, but I didn't find anything that fits yet.