Question: [![lotr meme](https://i.stack.imgur.com/SsEzO.jpg)](https://i.stack.imgur.com/SsEzO.jpg)
i know smeagol and gollum are basically the same person, but what does it mean in this meme?

Answer: 
I think the students will look at it form **their** perspective. Unless something warns them, the audience will likely look at it from their perspective. An experienced orator would be aware of this and pick their words carefully.

To clarify, the teacher (as he stands in the picture, facing the class) might say ***my*** left-hand side (yellow), or ***your*** left-hand side (red).

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As I suspected, there is a distinction. I don't know anything about hearts and muscles, but that doesn't matter. The speaker is using the **middle** of the image to distinguish the left and right sides. As a casual observer, I understand his words to mean that he is talking about the purple and yellow figure. Whether or not it is accurate is not a matter of English usage.

There is also the possibility that he is referring to the entire image. Before the video cut to this image, he was standing to the right of the image, facing the viewer. If in his mind he does not know that the video will cut to this image, and he has a live audience in mind, then referring to *the left-hand side* would be with respect to the audience's perspective and it would include the entire image.
> 
> *If you look at the diagram on the left-hand side...*
> 
> 
> 

If there is only **one** diagram, this phrase refers to **the left-hand side of the diagram**:

![](https://i.stack.imgur.com/dJHzU.png)

However, if there are **two** diagrams, the phrase refers to **the diagram on the left**: 

![](https://i.stack.imgur.com/07hKF.png)

So, **if you look at the *first* illustration on the left-hand side**, you can see the carbon ring in the molecule. **If you look at the *second* illustration on the left-hand side**, you can see the normal foot and arch. 

As other answers have pointed out, most often, this is from the perspective of the **viewer**. 

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Therefore, in your example, 

> 
> ...if you look at the diagram on the left-hand side, it explains what these intercalacted disks are.
> 
> 
> 

That is referring to the diagram with the purple and yellow columns: 

![](https://i.stack.imgur.com/rVddR.png)