The Ever-Evolving World of Science
The journey through this book
Take a quick tour of the topics you will explore in this book.
The book covers physics, chemistry, biology and earth science. They look like separate chapters, but they are all interconnected: an idea in one area often inspires a discovery in another, or at least a new question there.
Here is the year, in the order of the book:
| Topic | A question to start with |
|---|---|
| properties of materials | Why are some fruits sour? What happens when we wash a haldi stain on a school uniform? |
| electricity | What materials do we need to make a lamp glow? |
| metals and non-metals | How can we sort materials by their properties? |
| changes | Which changes can be undone, and which cannot? |
| heat | How does heat flow, from an ice cube in a glass to a melting glacier? |
| our growing bodies | Why do our bodies change so fast in the middle-school years? |
| life processes | How do animals, and plants, get food and breathe? |
| time and motion | How do we measure time, and how fast does something happen? |
| light and shadows | How do we see, and how do shadows form? |
| Earth, Moon and Sun | What causes day and night, and eclipses? |
Changes. Some can be reversed and some cannot. Butter melts in the sun and sets again in the fridge: reversed. Break an egg into a pan and try putting it back in the shell: impossible. The book lists batteries running out, ice melting into water, fruits ripening, rocks breaking into pebbles. Some changes happen, or happen faster, when things are heated.
Shadows and time. Long before clocks and watches, early humans watched the shadows of objects in the Sun and used where the shadow fell to tell the time. A sundial works this way. The Jantar Mantar in Delhi and in Jaipur has huge sundials you can still visit.
Shadows in space. The Earth and the Moon cast shadows too, and that is what gives us eclipses. Day and night depend on light from the Sun, and on the Earth turning on its axis.
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