Yes. When being assessed by the assessor on the water, prior to heading off, the assessor will issue you a written test. The test covers navigation, tides, buoys, weather and other areas. You should be very competent at these tasks. All tasks for the assessment are listed in your curriculum under the OTW assessments downloadable PDF.
For any area of the assessment, which you are not fully comfortable with, you should communicate that with your assessor beforehand so that you can gain some training. The assessor does not want to issue you a lower competence grade but will do if you demonstrate weakness that will endanger you or your crew or the vessel. Don't try to "wing it".
This written theory test is NOT the same as the online SLC free exam.
The SLC is the Mediterranean sailing license that NauticEd is able to issue.