Earlier, you looked at your XO with the power off, and observed much. You found lots of questions, and not so many answers. Now turn your XO on, and explore further.
Let's try the screen hinge and swivel. How far does the screen move, up and down or side to side? Rotate the screen left or right as far is it will go, and make notes. Do you notice anything when you have turned it as far as it will go? Hint: I just gave you a hint. Can you see where I did that? Did it help?
You should have tried the button with the two arrows pointing around each other. What happened? Did you try it again? Do you understand it? Does this give you any ideas about the screen swivel function?
The undiscoverable: There is no way I know of to lead you to the nature of the three USB ports without coming out and saying it or physically showing you by plugging in an external mouse or keyboard, or some other device. In a classroom, it might be that having XOs and things that plug into them would inspire some child to try it. I don't know. Perhaps we should try the experiment. Of course, if you knew about USB ports already, you didn't need me to tell you. Do you know how USB works? Do you know how to look it up? What can you plug in? What do you think you might want to plug in? Notes and questions.
Similarly, the slot underneath the screen section takes flash cards to expand the XO's storage, or to store an alternate operating system. Possibly Windows, or a full Linux distribution like Ubuntu. You can also use flash cards for data transfer from other devices. To use a card, turn the screen sideways to get access, then slide the card in until it clicks.This latches it in place so that it will not fall out, and you can't just pull it out.
This is a tough one that caused much trouble in the earliest days, when XOs didn't have manuals or a guide like this one. To remove a card, do not just pull. Push gently inward until you hear a click, as the latch releases, then pull the card out.
Have you ever heard of Sneakernet? Before local networking and the Internet became common, people would walk floppy disks or other antique removable media from one computer to another in order to transfer files. We expect that there will be XOs in places without Internet, where it will be important to take CDs or DVDs, or USB flash drives or flash cards, from one computer to another, or one village to another.
XOs can't read or write CDs and DVDs without an external USB drive, but the XS school servers will have optical drives, and will share files with the XOs in the school.
The green swivel bits are Wi-Fi antennas. They work best in the upright position. They are also the latches for the XO. Did you find the latching mechanism?
Any questions? If you have been doing as I suggest, the correct answer is, "Yes, lots." Contrary to the common experience of schooling, when we are done with my suggestions you will have many answers, but even more questions. That's life. Rocks don't have questions. People without questions are actually or effectively dead.