I've had problems like this on and off in the iOS app. Ways in which I've gotten around it:

1. Have some patience, especially if you have a slow Internet connection. (Ha! Here I am, one of the least patient people in the world, telling someone else to be patient. But I have found that waiting a minute or more when using Khan Academy on my iPad sometimes pays off when something doesn't load right away.)

2. Close down your iOS app (but don't sign/log out) and switch to the web version of Khan Academy for this exercise. You should have Safari or another browser on your device. Make sure you are logged in on the web site. (The same user ID and password you used in the app works here.) If you weren't logged in on the app to begin with, what I'm going to explain here won't work properly. If this is the case, you likely won't get a shot at this question/problem again, and you won't get credit for the earlier problems/questions you already did within the exercise, unit quiz, unit test, or course challenge.

Navigate to the course you are taking, then to the subtopic, and finally to the practice exercise, unit quiz, unit test, or course challenge you were attempting when you had this problem. The problem you were stuck on should be the first one you see, even if it wasn't the first one in the exercise/quiz/test/challenge you were in the middle of. (Occasionally, this type of transfer does make an earlier one come up first. If so, try to answer them correctly before the one you got stuck on comes up again.

If the graph still doesn't show up, have patience again.

3. If the graph still never showed up, even in the web browser on your device, and you have access to a desktop or laptop computer (Apple or Windows), use this to access the web site.

4. Regardless of how you finally got this to work, and especially if you never did get it to work, use Report a problem at the top of this page, to the right of center, to let Khan Academy know of this problem. Do not expect an immediate fix. I see problems I reported months ago still showing up in this Support community.

What would be great is if a problem could be skipped, especially if you’ve tried both the app and the website. A special graphics did not load button that would report also, killing two birds with one stone.