I believe CER's or CLAIM, EVIDENCE, and REASONING tasks are fundamental in navigating life in general and are things that humans do on a day to day basis. I feel that this action within the classroom is essential when done correctly since it can allow students the ability to engage in content in a humanizing way.
Students may have had to perform a CER or have seen their parents perform a mental CER with a scenario like this. It is raining, we need to get inside a store, where should I park based on these conditions, do I have materials to support my decision on where we park?
Instance #1: You do not have a jacket, a pancho, an umbrella, etc., and you do not want to get wet. Where do we park?
With this evidence of lacking anything to keep you from getting wet in the rain, you can then assume a claim for yourself would be "I need to park as close to the store as possible because I do not want to get wet." Your evidence/reasoning depend on what you have or do not to keep you from getting wet and what parking spot you should choose based on these factors/which ones are available. This is rudimentary in a sense but the principle to me seems the same as a content based CER.
Recently the students within my classrooms had to perform a CER that revolved around coral bleaching based upon oceanic temperatures. The students read a brief excerpt about why coral reefs bleach, the significance of this phenomena, they were then given different data tables that illustrated bleaching based on oceanic temperatures. The students were then to write a CER on bleaching being caused by oceanic temperature differences. I feel like most students were able to make a claim, look at the evidence, however they seemed to have trouble linking the evidence or rather multiple pieces of evidence into their reasoning. I feel like this demonstrated the need to have students being provided a scaffold where they could list out the evidence, be provided an exemplar scaffold with the evidence being shown in the reasoning (all the pieces), and students could then attempt the complete CER on their own. This may be an issue solely in 6th grade, but I do think that formatting or articulating thought can be a difficult task as we primarily make arguments in our day to day lives verbally.
Perhaps having students jot down decision making they perform outside of the classroom in a CER type journal could be helpful for them to see that they do this daily? Then they could possibly make the link between doing it within a classroom structure as being synonymous to the argument they have with their sibling when choosing what to watch on T.V.? Either way, I feel CER's show students they understand content when completing them successfully and can be a "full circle" type moment of them applying what they have learned in the classroom with their own assertions.