Correct sentence: Sloths climb down from the tree once a week to poop.
Child-friendly alternative: A sloth climbs down from the tree once a week to go to the bathroom.
- Subject: "Sloths" tells who we are talking about.
- Verb and place: Use "climb down from the tree" (adding "from" sounds more natural than just "down the tree").
- How often: "Once a week" tells when this happens and is in the right place after the action.
- Purpose: "To poop" explains why; for younger children, "to go to the bathroom" is a nicer phrase.
So the best version is: Sloths climb down from the tree once a week to poop. Great job checking your sentence!