Notebook Correction 7/27/2016

I received an alternate correction on the notebook entry I made yesterday. It's kind of an overhaul (and therefore slightly discouraging), but I'll try to take it in stride and learn from it what I can.

Original:
ジョン：　学校に行きたくないよ。
レベッカ：　なんで？
ジョン：　スミス先生と授業はぜんぜん楽しいですから。
レベッカ：　でも、いつも映画とかを見せる。
ジョン：　うん、だけどとても退屈だよ。
レベッカ：　たぶんそうだね。

Corrected:

ジョン「学校に行きたくないよ。」
レベッカ「えっ？なんで？」
ジョン「だってスミス先生の授業つまらないもん。」
レベッカ「でも、いつも映画とか見せてくれるじゃん？」
ジョン「うん、だけど退屈だよ。」
レベッカ「うん...  確かにそうだね。」

First, he added quotes to each line. Not particularly important to me since I don't really care how each line is formatted. Next, he added えっ to Rebecca's first line as kind of a "huh?" Fitting, and I originally debated adding that, but I left it out mostly because of laziness.

Next, he began Jon's second line with だって, which is kind of a colloquial "because." That also leads to the removal of the から at the end of the line. He also changed what should be ぜんぜん楽しくない to つまらない, which means "boring" as opposed to "not at all fun." Finally, he ended the sentence with もん. A dictionary tells me that もん can be used at the end of a sentence to indicate a reason or excuse, so that makes sense with Jon's explanation here.

In Rebecca's second line, he used my original 見せる, then conjugated it to the progressive form. That sentence is ended with じゃん, which is a contracted form of じゃない and says something like "isn't it?" So with those two changes in place, the sentence reads as "But he's always showing us movies and stuff, isn't he?"

With Jon's third line, he only removed the とても, so it's merely saying "yeah, but those are boring." I think とても comes off more as "very", so saying something like "yeah, but those are very boring" doesn't sound as natural.

Finally, the last line is completely changed to a different expression. 確か means "sure" or "definite", so this sentence sounds like a "yeah, I guess so, huh." That also sounds natural as a response to Jon's proclaimed boredom.

Despite that being a lot of changes, there's actually a number of useful grammar tips here, so I'm going to keep this post in mind for future reference.