To attain success in the development of your product and business as well, Six Sigma philosophy is taken into account. However, I have come across many people who misunderstand Design Thinking for Design of Six Sigma (DFSS). But, let me tell you that instead of the presumptions of most of the people, Design Thinking and Six Sigma are two different things, but aren’t mutually exclusive. 

Let me give you a closer view of the concept of Design Thinking and Six Sigma:

With the help of Six Sigma, you can systematically improve the design service or product of a business. It involves methodology, rigor, and tools in the process. 

The way designers think is referred to as Design Thinking. Designers visualize, hypothesize, experiment, and iterate and then come up with the final output. The variety of tools that the designers take into consideration is: 

• Mind Mapping
• Journey Mapping
• Assumption Testing
• Storyboarding 
• Co-creation
• Rapid Prototyping and piloting
• Visualization, and
• Learning launch

As a practitioner of both the approaches the very significant difference between Design Thinking and Six Sigma is that the former process is iterative but permits linear progression and the latter is linear which allows iteration. While Six Sigma focuses on data rigor, which is the less imaginative aspect, design thinking depends on imaginative rigor. 

This proves that Design Thinking and Six Sigma are not mutually exclusive and is rather co-dependant with exactly opposite nature. Also, Design Thinking has experienced immense traction in the Service Sector. The main reason behind this is that service sectors never follow any sort of rigorous procedure. 

For Designing of Sigma, there are two most important frameworks namely:

• Identify-Design-Optimize-Verify (IDOV)
• Define-Measure-Analyze-Design-Verify/Optimize (DMADV)

With Six Sigma you can have a systematic approach to improve the design of the product and the service as well. 

I believe, we don't have courses of design thinking on Khan Acad. 

Still if you are keen to study Design Thinking, you can visit coursera, edx, great learning.