the advantage of gravel is :

the disadvantage of gravel:

the advantage of sand
the disadvantage of sand

Here's a website that discusses using sand and gravel in hydroponics.

http://www.frogchorusfarm.com/growingmediagravelsand.html

However, I'm sure it will be easier for you to find these answers in your science book.

our teacher took our books

weight is a strong disadvantage to both

sand disadvantage is it stays wet
advantage of gravel: air gets to root hairs.

For my orchids, I have found expanded clay particles are superb. I add 1/2 expanded clay, 1/2 shredded rubber tires.

The advantage of gravel is that it provides good drainage and helps to prevent soil erosion. Gravel allows water to pass through easily, preventing puddling and waterlogging in gardens or landscape areas. It also keeps soil in place and reduces the risk of erosion caused by wind and water.

On the other hand, the disadvantage of gravel is that it can be difficult to walk on or drive over. Due to its uneven surface, gravel can be challenging to navigate, especially for people with mobility issues or when using narrow-wheeled vehicles. Additionally, gravel can scatter and get displaced easily, requiring regular maintenance to keep it in place.

As for sand, its advantage lies in its ability to improve soil drainage, retain moisture, and prevent compaction. Sand particles have larger gaps between them, allowing water to flow through and preventing excessive saturation. It also aids in reducing the risk of soil compaction, which can lead to poor plant growth.

However, the disadvantage of sand is that it does not retain nutrients well. Unlike fertile soils, sand does not have the capability to hold onto essential nutrients needed for plant growth. This means that frequent fertilization is required when using sand as the primary soil component.

To summarize, the advantages of gravel include good drainage and erosion prevention, while the disadvantages involve difficulties with walking or driving over it. Sand, on the other hand, benefits the soil by improving drainage and moisture retention but lacks nutrient retention capabilities.