The "Teacher Tools" pop-up can be found to the bottom right of every SentenceBuilder on SentenceBuilders.com
This pop-up offers all sorts of options for exploiting the SentenceBuilder for front-of-class interactions.
Random L1 prompt
If you select the "Random L1 prompt" (in this case English) option, a random sentence -- selected from the potentially thousands of available sentences -- appears below the SentenceBuilder.