I decided to explore the <know> word web with Mars (age 8). I asked him to read the base <know> and then tell me what sound it starts and ends with. That's where the /n/ and /w/ came from (my attempt to describe the sounds without using IPA). I said we'd take turns putting words on.
(As with everything I'm doing right now, I'm trying not to be inaccurate, but I'm inevitably making mistakes as I practice using SWI to work with my kids.)
Me: I can think of a word that adds a suffix to our base <know>, and the suffix is only one letter. [I leave the room to help my other child.]
Mars [to himself, slowly]: Knew. Knew. Hm, how do you spell "knew." [He writes "kno."]
Me [coming back]: Good job. Can you write it? How do we spell "knew?" Here's a hint: only the vowel changes.
Mars: So I write a <u>?
Me: Ah, good. The vowel changes, and I'm going to tell you that it changes to an "e." [Mars adds <knew> to our web. I add <knowing>.] What suffix did I add here? Can you underline it?
Mars: "Ing." [I encourage him to spell it out.] "I-n-g."
Me: So which part of <know> and <knowing> is the same?
Mars: Just "know." [I ask him to spell it out, but I could do so myself, modeling spelling it out and grouping graphemes.] "K-n-o-w."
Me: That's the base. Any other words to add?
Mars: "Knowed." [I ask him to use it in a sentence.] "I knowed it." But it's <knew>.
Me: [Clumsily trying to guide him to <knowledge>.] What if somebody has a lot of "blank" in his head. He has a lot of...."
Me: Good. Let's write that down here at the bottom of the page. Thoughts is related to knowing. ["Related" was not really the right word to use here--related in meaning/conceptually, not related morphologically/etymologically.]
Mars: What was it?
Mars: Oh, I thought it would have to... [I think he was thinking about the vowel sound changes here.]
Me: It's in the family, so it has some of the same letters. "Knowledge."
Me: Gnawing! Are you thinking of chewing? [Next time, ask what meaning he is thinking of.] Let's write that down here. What suffix did I add to <know> to get <knowledge>? Can you underline it? [He underlines just the <l>.] Is that all I added?
Mars: [Sounds out "e-d-g-e."]
Me: What about something that you don't know? It's...
Mars: Unknown. [Adds it to web. Underlines prefix when I ask him to.]
[We add some prefixes and suffixes from the web to our new prefix/base/suffix sticky note chart.]
Mars: You didn't do "gnawing."
Me: Oh, right. What does "gnawing" mean?
Mars: [Pantomimes chewing on his arm.]
Me: Does that have anything to do with knowing? [Mars shakes his head.] No. And they're not related. And see how they have a different initial letter?
Mars: But knowledge!
Me: Oh, right, you're hearing the same phoneme in both words. [I make the "ahhh" sound.] Great that you noticed that.