Do I need to ask permission to provide a narrative of a scholar's methods? I am writing a secondary school archaeology and history textbook. I'm inspired to adjust the book based on two types of students:

Some are excited about what they are studying, and tell their career counselors they want to be archaeologists/historians.
Others have grown up believing scientists are liars, and are just messing around creating a big conspiracy of &quot;Fake News&quot;.

Based on this, I don't simply want to have a textbook that says &quot;this happened&quot; or &quot;this is how they lived&quot;, but I want to also show students what steps the scholars actually too to arrive at their conclusion.
That means I'm digging through journal articles to identify which scholars came to those very detailed conclusions, and converting their &quot;Methods&quot; section into easy-to-read narratives:
Sam Spade was an associate professor at the University of Arizona. He wanted to find out
when the Hohokam switched from eating big game to farming. He sent graduate students to
collect thousand-year-old samples human feces from various archaeological sites. The Hohokam
people tended to leave this in areas near... Back at a lab, Sam used a machine called a 
radiocarbon dating...

In a traditional textbook, Sam Spade's research would merely receive a footnote, but here he's considerably elevated in status, and his work presented in narrative form. This unknown scholar is presented as someone important.
Given how I'm using this information, is a simple citation of the work still sufficient, or do I need to be sending each and every scholar a detailed letter asking permission, and describing how their name and work is going to be used?
For writing a narrative about published research in your own words, you need a citation and that's it.
For quoting directly from short passages of published research, you need a citation and indication that this is a direct quote.
For images/figures you likely need permission from the publisher unless the images/figures have been released with a license that allows you to reuse them (you'll have to check for each individual image) or if your use falls under some form of &quot;fair use&quot; (the term is used in at least US and UK copyright rules; similar doctrine may be present in other countries). Writing a textbook you intend to distribute/sell is probably not fair use. Putting the figures in a slide show for educational purposes of your own class probably is.
If you were writing an entire book about one (living) subject I think it would certainly be good manners and perhaps a useful collaboration if you were to contact them and get their blessing, but it would not be strictly necessary to do so. It sounds like your intent is instead to provide narrative research descriptions from many different scientists at an appropriate reading level for your target audience, so I don't think it's nearly as important but you might still find some benefit to reaching out to some - scientists are typically excited to share their work, especially if it's an opportunity to spread their research area to the next generation.
Lastly, I'd urge a bit of caution in your approach. Papers these days are typically written in ways that suggest that science is clean and linear, when in fact it is often messy and circuitous. Your approach seems to make it even cleaner and more linear. It's common for textbooks to take this simplified approach to historical experiments, but it doesn't necessarily convey what science really is to people who may be interested in pursuing it. The conflict in expectations can be quite distressing when it is first encountered.