My family enjoys this English language Little Midrash series.
Does something like an English language 'Little Gemarah' (ie introduces reasoning logic) exist for children 6-12 years old?
Here is Masechet Yevamot broken down into worksheets per daf. I am unclear what ages they are meant for, but they do seem very colorful and something somewhat appealing to a younger scholar. (They've even printed some of them)
However, since you adressed preparations in Gemara-logic, I recommend this, which is exactly for that: