You need the following hardware to organize classes in robotics. Different robotics sets and software could be used. Here are our recommendations. Most of our courses are based on these sets.
08  12 years
LEGO Mindstorms EV3
Mindstorms Sets

Two students work with 1xLEGO Mindstorms 45544 and 1xLEGO Mindstorms 45560. We call this a Double set

Each double set is around 600800$.

You need 6 double sets for a single group.

For a double set, you need 1 computer (preferably laptop).

Double sets are reused for the different groups. In the morning a group works with the sets. In the evening, another group works with the same sets.

Example: Our largest academy has about 50 double sets and about 400 students are using them each week.
Each group is of 1012 students.
Notes
 Don't go for Boost and WeDo for 810 years old students. These sets are for even younger students and you can do very little with them.
13+ years
Perfect Pi Set(s)
Raspberry Pi sets for The Perfect Stem Course

Two students work with 1 or 2 Perfect Pi Set.

Each set is around 150200$.

Preferably each student buys and works with his/her own set and continue using it in other courses after that. The hardware is also partially modified.

You need at least 6 perfect pi sets for a single group.

For every two students, you need at least one computer (preferably laptop).

Perfect Pi sets are hard to be reused during the course. The hardware is modified. But after the group is completed most parts like controllers, batteries, drivers could be reused.

Students must have smartphone. Software will be installed on the phones and it will communicate with the hardware.

Example: Our largest academy has about 10 perfect pi sets that could be used in groups, but in 95% of the time students have their own sets.
Each group is of 1012 students.
Tetrix/Matrix sets
Tetrix

A team of 5 to 10 work with a single Tetrix set

Useful for preparing for competitions

Example: Our largest academy has about 10 perfect pi sets that could be used in groups, but in 95% of the time students have their own sets.
The more parts you buy the larger robots you would be able to build.