Print these signs out on colored cardstock, laminate and provide a set for each student desk.
When the kids need help, they can post the "Help" sign.
When the kids are okay, they can post the "Ok" sign.
When the kids are great, they can post the "thumbs up" sign.
This is an Excel file, so you can adjust the size for your purpose.
This will be a great visual tool while walking around the classroom.