There isn’t much discussion for this chapter!
I bet like me, most people skipped the challenges.
TalkBack seems like a great idea, but is unfortunately very buggy - at least on my Samsung Galaxy S5. It was extremely difficult to unlock my phone with TalkBack enabled and I momentarily panicked thinking that I might not be able to unlock it at all. Using the on-screen keyboard was close to impossible - TalkBack continually insisted that I had pressed a key that I had not (on the other side of the screen) making text input close to impossible. I was very relieved to turn TalkBack off at the end of the main chapter content!
On YouTube there is a 6 minute video with 200,000 views explaining how to turn TalkBack off on the Galaxy S5. Read the comments for some amusement!