Conditional Text or Layers for Workbook answers?

[Vicious Celery]

Hi, folks!
I'm responsible for creating workbooks for our learners, and I also supply an instructor's version with all of the answers.

I've used layers for many years, where the student version, with blank lines, is on one layer, and I can turn on the "Answers" layer to show the answers when exporting the instructor's version. Answers might be text, or they can also be images in many cases. When I combine this system with the layers per book script to globally turn the "asnwers layer on/off for an entire book, it's pretty slick. However, the layers system gets annoying when there is a change to a question, since I can't anchor the content in the Answers layer to  the blanks they belong with.  I need to carefully go through the rest of that document and make sure everything is still in alignment.

Would it be better to use conditional text instead of an Answers Layer? My understanding is that I can't use anything other than inline images for conditional text, but maybe I can work with that restriction...

I'm hoping to lean on you all for for opinions, regrets, past experiencs, foreseeable difficulties, etc!

This is a typical worksheet page, with blanks to be filled in, boxes for letters to be matched to, etc.

This is a screenshot of the Instructor's version, with answers filled in. (Currently using layers to do this.) As you can imagine, it's annoying if a question is changed and I need to keep up and keep the answers matched. 

[Willi Adelberger · Accepted solution]

I did such a book, but I did not use conditional text. I wrote the answers dirctly in these form lines with another font. The student’s version got text with color none, in the Teacher's version the text color was changed to a visble color.

[Willi Adelberger]

The color change was done in changed paragraph/character style.

[Vicious Celery]

Sneaky! Could that also work with images?

Since I have multiple worksheets that combine into a book, as long as I sync styles across the book, that would propagate the change. Seems very workable.

Thank you! (I'd love to collect as many opinions as folks want to give, so I'm going to hold off on marking this answered for now, but I appreciate it!)

[Willi Adelberger]

What kind of images?

[Vicious Celery]

Anchored inline, where I'd like to swap the entire image between  student's view and an instructor's view.

Here, you can see the student version of a schematic, and the instructor version that it swaps for, below. (currently using conditional text)

[Willi Adelberger · Accepted solution]

Try to use an object style which will make the opacity 0% either to the whole object or to the content. This can be switched globaly by changing the style with one click.

[Eric Dumas · Accepted solution]

How about using Windows > Object States?

Until InDesign gets 'Layer Comps' like in Photoshop, having the answers on a separate layer might be the quickest

[Vicious Celery]

I haven't tried out object states - thanks for the tip!

In case anyone else comes along and reads this in the future, I think I am going to limp along with 2 methods - one for text and one for images. I'll use the suggestion of 0% opacity for answer text, which allows me to keep it in flow. I'll do images by anchoring them and making them conditional. (Unlike the text, I don't want the images to take up space when they're not active.) This means I will need to make 2 changes to each document when I want to export the different versions, but the payoff is that the answers will always stay in flow, so I don't need to worry about them getting misaligned. The other disadvantage is that InDesign is really running slowly now that I have added conditional text. Hoping this might be temporary.

If anyone from the future is reading this, feel free to reply to this message and ask how it all worked out. I'll probably have a lot more thoughts on it after mantaining this project for some time!