I detest putting things in alphabetical order. Alphabetizing is one way of organizing information and works well for such things as phone directories, but people don't remember names, words, or concepts in alphabetical order. Instead, our memories tend to work by association. We connect new things to things we already know. To take advantage of the way memory works, I try to establish clusters or groups of related ideas, and keep between 3 and 8 items in a group.
Science is one of my personal favorite areas of study. As I organize information, this includes the physical and natural sciences, not the social, behavioral, or technological sciences. Specifically, I recognize 5 major areas:
1) Physics. Mechanics, electromagnetism, thermodynamics, and structure of matter.
2) Chemistry. Chemical substances, changes and reactions, and chemical systems
3) Astronomy. Planetary astronomy, stellar astronomy, galactic astronomy, and cosmology
4) Earth Science. Geology, Oceanography, Atmosphere, weather and climate; Physical geography, and Earth history.
5) Biology. Molecular biology, cell biology, organisms, ecology, and Biological history.
Science is a human endeavor, and scientific investigation is done by individual people, with their characteristics and limitations. It is also a social endeavor, subject to other characteristics that influence society. It makes use of ideas, patterns of behavior, and technology. There do not seem to be strong connections with families, but this is closely connected with education, and there are connextions with economics, government, and religion. The communities and peoples of the world have somewhat varying emphasis on science. It is possible to distinguish between the history of nature, and the history of science (the human study of nature), and which is to be treated where and how is up to the student.
For exercises, spend some time outdoors. Watch the trees, grass, or whatever grows where you live. Examine the shape of the ground; bend down and examine it closely, for insects and small things. Watch the sky and the clouds. Look at the stars. Pay attention to things and what they are made of; to light, color, temperature, size, shape and weight. Then, write down any questions that occur to you about hows and whys of how these work. A child-like curiousity about the world and how it works is at the root of scientific research.