To find out type of memory?

I should find out after my teacher in the device manager, the type of memory but where? Have a laptop with Windows 10

I would recommend you the small tool CPU-Z. Everything is listed what you want to know.
https://www.cpuid.com/softwares/cpu-z.html

I would have recommended that too. Very good tool for analysis. Just like GPU-Z.

Task Manager is often sufficient to read the clock rate there. If it is 2133 MHz or 2400 MHz, then it could very probably also be DDR3 RAM, but is really very unlikely.

If that is the case then you need e.g. The tool CPU-Z: https://www.cpuid.com/

Right-click on Task Bar
Go to Task Manager
Go to performance
Go to RAM
Kuck down the things like size, type, usage, cache, speed, form factor, slots used etc…