An adaptation of the Catechism for Young Children in modern English.
Question: Does God know everything?
Answer: Yes; nothing is hidden from God.
Question: Does God know all things?
Answer: Yes; nothing can be hid from God.
Substituting “all things” for “everything”, see note on Question 2. Substituting “is hidden” for “can be hid” for more direct phrasing to emphasize God’s knowledge rather than human’s inability (c.f. Hebrews 4:13 ESV/NIV).