Responding to my question, the delivery person told me Amazon.com has facilities in Changi South. I had thought Sing Post would make the delivery. I think our national post office has gradually been squeezed out of business.
Why all Science books? Well because they are either too overpriced or not available here. Just science books, the kids wouldn't read. It must be interesting and persuasive. That is why it is so hard to find the right books. I remember we used to own every titles of the Magic School Bus series when they were younger.