This looks like it was an oversight on our part when making the exemplar. Sometimes that’s because the exemplar was created based on an earlier version of the curriculum, and sometimes it’s just because we made the exemplar in text mode and never realized that it was impossible to recreate using blocks.
For most blocks, there is an arrow that allows you to display and hide the openings for the optional parameters. In this case, I think that we changed the way that the block originally worked, so the expected arrows don’t show up.
Regardless, I’d consider issues like this “bugs” in the curriculum. The exemplar should be something that students could reasonably do given the resources they have available. Please feel free to report these problems as bugs in by choosing “Report a Bug” from the menu at the top right of Code Studio. This is the fastest way to get it on our to-do list.
I’m logging the problem with this exemplar so that we can correct it for the next version of the curriculum. Thanks for the heads up.