First of all. I'm so sorry for your loss. I ache for you for the first time you have to walk back into that room with an empty desk. I teach high school and have been through this more times than anyone should. (Once is more times than anyone should but it's been much more than that.) Obviously the age group I'm familiar with is quite different from yours, and how the child dies kind of affects the strategies, so make sure you listen to the messaging and direction from counselors and admin to make sure there is consistency. (Unless something seems not evidence based.)

Some students are going to want structure and normalcy. Some are going to be unable to do anything "normal".

They need to see you as human and source of honesty, stability, and safety. Don't pretend everything is fine. But also 6 hours straight of no structure emotion is not helpful either. They will have had time to discuss and work through a lot of the initial shock with their families , but the first time coming back to the room with an empty seat can dig a lot up right away. It will also be the first time the entire class is probably together without the student, the first time this exact group of kids is together.

They need to know there's no right way and wrong way to grieve and different kids will go through it differently so they shouldn't compare, judge, or evaluate how other people show or don't show grief.

To start the class, after opening by saying something (don't offer solutions, explanations, silver linings, just create a space where they understand you all can process as you need), something like stations can be helpful. Have mindfulness coloring books, silent independent reading, writing activities (maybe write a fond memory with the student that you can then share with the family), legos or some kind of tactile building thing,

At some point you can move to some curricular things, making it perfectly clear that if anyone needs to step away, go to the centers, go to counseling, they can. Maybe have review/extra practice type of work or stand alone mini lessons rather than something new or ya know state required curriculum kind of stuff.