Mind Matters is a 6 week social emotional workbook created by Kelly herself:

I created Mind Matters because I wanted students to understand the “rules” of social-emotional learning, and I couldn’t find a practical resource that did it. After years of working with students and families, I boiled it down to six topics and turned them into a hyper-practical set of ideas and tools. They help your child handle big feelings and big problems, spot mind traps, calm their body, build healthy friendships, and find their own voice.

It depends on your child.
Standard recommendations: 
If your child is going through a hard season, 1:1 may be better.
If you want these skills for their future but things are not particularly stressful for them at this time, classes may be better.
Each child is different and there are benefits to both.

I will mail the workbook directly to you with a handwritten note for the child.

Although no outcomes are guaranteed, many parents state they notice differences as early as the first 2 weeks. Other parents have noticed that they say they don't remember the class, but recognize they're using the skills that were taught. Each child is different and the child's willingness to participate greatly affects the outcomes.

I don’t offer a money-back guarantee for 1:1 coaching. Results depend on how much a student is willing to learn and put the tools into practice, so I can’t promise an outcome. What I can promise is this: every child in 1:1 coaching gets a caring adult in their corner, and research consistently shows that is one of the strongest predictors of thriving at any age.