You might not believe it, but there is a difference between the word in and into and when you use it. The easiest way that I remember it is that in is a static word. It indicates a position, but it’s not moving.
Whereas the word into is a word that indicates movement or something in motion. So, one way to think about is my blouse is tucked in. Nothing’s moving, it’s already tucked in, so we use the word I-N. But, however if I’m getting dressed and I’m actually doing the action of tucking my blouse into my skirt, we use the word into to indicate that motion is happening in the middle of the sentence.
Another way to visualize this is to look at the pencils on the desk. I’d say that these pencils are in the cup. But, now I’m going to put these markers into the cup. You could see because I was performing an action, I used the word into. So, I hope that that makes it a little clearer, the difference between in and into.