This is a great way for students to get to know the story of the Pilgrims who came to North America escaping religious persecution. It's especially pertinent to ELs whose families have fled their home countries for myriad reasons.
It's also an easy homework assignment that can include the whole family.
I read Molly's Pilgrim with my 4th graders as well--- there they talk about "modern pilgrims."
It's best assigned after a short unit on the Pilgrims or at least a couple of read-alouds before Thanksgiving.