Need help with managing class of 18-month-olds who won’t stay put or follow directions

Hi, I’m an ECE teacher with a class of 18-month-old toddlers. Lately I’m really struggling with group management — many of them run off constantly, ignore directions, and seem totally fearless. I know this is developmentally normal, but I’m having trouble keeping everyone safe and running activities that don’t fall apart after 30 seconds.

For those who’ve worked with this age:
What has actually worked for you? Especially when it comes to routines, transitions, and activity structure (circle time, movement, table work, etc.).

Real-life examples would be incredibly helpful. Thanks!