A reserve price is the minimum price the seller will accept. This price is hidden from bidders. To win, a bidder must have the highest bid and have met or exceeded the reserve price.
If you are looking for good, basic resource for your children in Science, then consider this. Yes, it's older, but it was published before school subjects were filtered through political-correctness and such. Their older-perspective is History in and of itself!
These are in GREAT SHAPE. They are Hard Covered. Like-New Condition.
They have been a great resource for our Home-Schooling years, and are loaded with pictures and detailed information.