Reference

Joshua 4:6–7 NRSV
Keys to Joy – Part Three – Never Forget

"so that this may be a sign among you. When your children ask in time to come, ‘What do those stones mean to you?’ then you shall tell them that the waters of the Jordan were cut off in front of the ark of the covenant of the Lord. When it crossed over the Jordan, the waters of the Jordan were cut off. So these stones shall be to the Israelites a memorial forever.”