Brief Answer:
I am so sorry, different possible ways to help

Detailed Answer:
HI, thanks for using healthcare magic

I am sorry for your loss.

There are five stages of grief but each child can experience these differently.... denial, anger, bargaining, depression and acceptance.

The depression and anger that he may display sometimes is part of the response that some kids or adults may go through but he would need to channel this anger differently so that he does not get into trouble.
Some children may not be able to deal with grief and may need additional help from a doctor.

(1) continue to talk to him about his mom. If he is not ready to talk, then maybe putting together a scrap book of his mother or looking at pictures or expressing himself by drawing, may be helpful for him

He may even want a keepsake to have with him

(2)let him know that you are grieving too, let him see that it is okay to be upset

(3)with regard to the trouble at school would need to let him know----I'm angry and upset that your mom is not with us as well, I miss her too but we have to have a different way for you to show how upset you are (something along these lines)
May ask him for ideas.
It may be a physical activity to help him get rid of pent up angst, may be a screaming session, it varies

(4)there are grief support groups for children that may help

(5)maintaining a regular routine as much as possible. Children are often concerned about the changes that will occur.
School and recreational/after school activities can help understand that as much as possible, things will go on.

There is unfortunately no clear cut way to deal with grief in children but if you continue to be unsure or he continues to act out then you may need to consider asking his doctor for help to speak to you or consider a grief group to help him express his feelings

I hope this helps, wish you both the best

Feel free to ask any other questions

---