Have a look at the cross-section of the femur and tibia. Explain what you can see. Is this part of the bone compact or spongey? Why?

Without an image, it's difficult to provide a detailed analysis. However, I can give a general explanation based on the anatomy of the femur and tibia.

1. The femur and tibia are both long bones, which are characterized by a hard outer layer of compact bone and an inner layer of spongy bone.

2. If you look at a cross-section of these bones, you would see a thick ring of compact bone. This part of the bone is dense and strong, providing support and structure to the body.

3. Inside the compact bone, you would see the spongy bone. Despite its name, spongy bone is also quite strong. Its structure, which looks a bit like a sponge, is made up of trabeculae (small, needle-like pieces of bone) that provide additional support and strength.

4. The spongy bone also contains red bone marrow, which is responsible for producing blood cells.

5. In the very center of the bone, you would see the medullary cavity. This space is filled with yellow bone marrow, which stores fat.

6. So, to answer your question, the outer part of the bone is compact, while the inner part is spongy. The compact bone provides the hard, strong structure of the bone, while the spongy bone provides support, houses the bone marrow, and helps the bone resist stress from various angles.