Summer of Math Exposition

Presented by 3Blue1Brown 3blue1brown

The Floor of Mathematics

Audience:

This video follows the creation of the natural numbers, integers, and rational numbers, and a great deal of the operations we use on them. I made it with the intent of being a introduction to real analysis, but since I didn't have the time to get that far, I decided to angle it towards how rigour and proof are so important to mathematics. I'd hope that it's of some use to someone who's in high school who's interested in learning maths at a more advanced level, as I hope this video acts as a light introduction into what that looks like.


Analytics

6.98 Overall score*
26 Rank
12 Votes
9 Comments

Comments

7

Your video is genuinely excellent, featuring a compelling introduction and beautifully simple visuals that enhance understanding, paired with clear, well-crafted explanations throughout. The production quality is impressive and your teaching style is engaging and accessible. The only consideration for future videos might be that the ambitious scope—while showcasing your breadth of knowledge—occasionally makes some proofs feel a bit rushed, leading to moments where they appear more briefly on screen rather than being fully explored. Even though I only made it to around the 20-minute mark due to time constraints, what I saw was high-quality content that demonstrates real skill in mathematical communication. Your work is already at a great standard, and focusing on a slightly narrower scope could allow your excellent explanatory abilities and production values to shine even more, giving each concept the full attention it deserves while maintaining the same outstanding quality viewers clearly appreciate.​​​​​​​​​​​​​​​​

5.4

Very long intro without writing.

6

The ideas in the video are well-formulated and rigorously handled with.

4.5

Erm, actually I think x\lfloor x \rfloor is the floor of math?? (I’m kidding)

I think what you’ve done here is impressive, but this topic is very tricky and I feel like there are a few cracks. In particular I have to say the way you’re communicating induction sort of gets my goat, the placement of the quantifier isn’t very clear in the written version that was given, and I think the animation could do a much better job of representing the fact that the inductive hypothesis is an assumption - that “P(n) -> P(n+1)” is something that a lot of your target audience struggles with quite a bit. There are some other weird inaccuracies like how your proof that no number is even and odd simultaneously doesn’t consider that the values of k on each side could be different, and some decisions about what could or could not be shortcutted through that I don’t quite agree with. (for instance, in a video about proving facts about these sets of numbers from first principles, I think it’s worth mentioning that FOIL, as something that a lot of students just memorize, comes directly from the distributive property)

I also don’t want to dock you for this because you’ve been quite ambitious, but there is quite a bit of length to the video, and the information isn’t very compartmentalized. I also think this length is likely the culprit of some of the slight miscommunications, since there was so much ground for you to cover. I’m not your boss or anything, but I think a slightly smaller scope could be beneficial in the future.

That said, again great effort here, I do hope you keep it up - I can see the potential

8

Incredible analogy with the construction of numbers and the buildings! Loved the video. I just think it was slightly tiring after some point, but other than that the explanations and visualizations were perfect!

6

You’ve chosen a good topic, and all the logic is easy to follow. This is a video about the foundations of math, so the emphasis on detail is appropriate, but it does come somewhat at the expense of intuition. For instance, why do we define the integers as differences? We’re coming to the right results, but it’s not clear why we take the path we do.

7.6

The video is very pleasant to watch, since the author has a quite a talent to teach and present this topic in a clear way. He reminds me of some of the great science teachers we have and I hope we will see more videos from him. Overall, I would say this is a very interesting topic for a wide audience, but in particular for high school students who are considering to study math or science.

Here are a few small items that I would suggest fixing:

When talking about induction, the statement says P(0), P(n) and P(n++) are true. Shouldn’t we say: P(0) is true and P(n) implies P(n++)?

9:43: The statement says n >= m “or” m <= n. This “or” isn’t in the mathematical sense. That looks a bit confusing to me. I would probably say (in a separate line) n >= m if and only if m <= n.

10:25: a is rewritten: a = a + b. But that implies that b = 0, so why not just rewrite a as a+ 0?

25:10: The audio says “rationals”, but it should say “integers”.

Overall, the video is fairly long. Would it make sense to skip the section on absolute values? Also, the pace in the proofs is often fairly fast, I would have preferred a slightly slower pace, at least in the first part of the video (the faster pace is OK once we established a few proofs).

These are just very minor comments. Overall: Thank you very much for creating a wonderful video that I hope will be seen by many people! You are an outstanding teacher!! I hope you will continue to share this talent with the world.

8.5

Not many pay much attention to these sorts of details. Well done. I can see a student finding their “Aha!” moment in deriving some o0f these abstract proofs.

4.5

Everyday material for mathematicians, but too formal for high-school students. The video is very long and could easily have been divided into several parts, given the wide variety of topics covered. One last suggestion: try adding summary diagrams and practical applications.