Helpdesk
If you are an English teacher and / or know the European Framework of Reference, you can probably easily determine at what level your students / classes need it. As a guideline you can use:
Beginners (Pre-A1)
Group 4/5
Discoverers (Pre-A1)
Group 5/6
Explorers (Pre-A1)
Group 6/7
Pioneers (Pre-A1)
Group 7/8, VMBO framework 1
Breakthrough (A1)
Group 8, VMBO-T 1-2, HAVO 1, VWO 1
Elementary (A2)
VMBO-T 3-4, HAVO 2-3, VWO 2
Intermediate (B1)
VMBO-T 4, HAVO 3-4, VWO 3
Upper Intermediate (B2)
HAVO 5, VWO 4-5