Each tag on your Thinglink project should include a caption of 25-50 words. In the library and museum worlds, these captions are viewed as interpretive acts. You are not just conveying information; you are attempting to provoke a response in your audience. When you have only a few words in which to do that, every word counts!
Beverly Serrell, in her Exhibit Labels: An Interpretive Approach, 2nd edition (Rowan & Littlefield, 2015) suggests that you focus on trying to answer the following questions in your captions:
The Getty Museum's Guide to Adult Audience Interpretive Materials suggests a very similar set of questions:
1. Go to thinglink.com and click "Start Now."
2. Select "Create an account," and choose the "free teacher" account.
3. Click "Create," then "upload image." At this point you will upload the high quality image of the artifact you've chosen from the list.
4. You are now ready to begin annotating your image!