Assuming there are five days of VBS, they might be tied together by the idea of Ark:
1. Noah's Ark
2. Baby Moses' Ark
3. The Ark of the Covenant
4. Mary as the New Ark
5. The tabernacle in church as Ark.
There will be good stories to tell, read, and act out; things to draw, color, and craft. Any of the stories could be expanded per time available, e.g., Baby Moses' Ark could be preceded by Joseph and the famine that brought his family to Egypt, and/or followed by the story of the first Passover. Then the kids could choose to make or draw: the pyramids; a sphinx; Joseph in his coat; Pharaoh; Moses in his Ark; the Burning Bush; one of the plagues; the Angel of Death passing over a house marked with lamb's blood; parting the Red Sea, etc. Then they could assemble what they'd done in chronological order and as a group retell the whole story by referring to their artwork. Maybe each day's artwork would append to the previous days' such that on the last day they could tell the whole connected story to their parents or another class.
The Bible would be treated in an organized way, and the kids would see a meaningful thread of Catholicism run from the Old Testament through the New, and on into the kids' very own church. Time permitting, a 6th Ark might also be squeezed in: the cube-shaped New Jerusalem of Revelations. And as a prelude to arks, the garden of Eden.
Ya can't beat that.