thesis statement = statement that is for or against something.
thesis statement is not: let's look/discuss...
Use of sources: often not done at all
or
not cited in the text (but well done for looking them up!)
Slide 2 - Slide
Sources substantiate
"The weather will be agreeable tomorrow."
vague & subjective
According to AccuWeather, the temperature will be 20 degrees at noon tomorrow, and it will be dry and sunny (AccuWeather, s.d.). Therefore, the weather will be agreeable.
substantiated with a source, in APA-style
Slide 3 - Slide
Same example in a structure
Agreeable weather
20 degrees (AccuWeather)
dry and sunny (AccuWeather)
Slide 4 - Slide
It takes space, doesn't it?
Indeed, if you substantiate what you say, you need to use more words.
However, it is an academically responsible and therefore required practice.