How can I test just some lessons, for example all double lessons or all PE lessons

Sometimes it may be usefull to try to test if you can put some group of lessons into the timetable.

For example put in all double lessons or all divided math lesson.

This is possible:
1. click right mouse button in the bottom part where the unplaced cards are shown and select Filter.
More on filter can be found here:
How can I filter cards displayed in the list on uplaced cards

2. Click right mouse button again and select Test. The software will now try to place all the cards into your timetable that match the Filter options selected in the first step.