[header] How to effectively observe a usability test [title] Follow your script. [substeps] Do not deviate from this. Otherwise you run the risk of interjecting your opinion into the test. 
[title] Watch the body language as the subject interacts with their task. [substeps] Are they following the instructions word for word? Do they look confused? Are there any hesitations before or after completing a step? [title] Ask the participant to say out loud what they are thinking.