Food — Class 3 Science (Samacheer Kalvi)
TN State Board (Samacheer Kalvi) Class 3 Science. Nutrients, a balanced diet and a home garden.
1. The five nutrients
Food does several different jobs in the body, and each job is done by a different nutrient.
| Nutrient | What it does | Where it comes from |
|---|---|---|
| Carbohydrates | Give energy | Rice, wheat, ragi, idli, dosa, potato |
| Proteins | Build and repair the body | Dal, milk, egg, fish, paneer |
| Fats | Store energy for later | Ghee, oil, nuts, coconut |
| Vitamins | Protect against disease | Fruits, greens, vegetables |
| Minerals | Build bones and teeth, keep blood healthy | Milk, salt, greens, ragi |
The short version: carbohydrates and fats give energy, proteins build, vitamins and minerals protect.
2. Carbohydrates are not the enemy
You may hear that rice and other carbohydrates should be avoided. For a growing child that is poor advice.
Carbohydrates are the body's main source of energy. A child who runs, plays and studies needs that energy every day. What matters is eating a sensible amount alongside the other nutrients, not cutting them out.
3. A balanced diet
A balanced diet contains all five nutrients in the right amounts, plus two more things that are easy to forget.
Fibre comes from vegetables, fruit skins and whole grains, and keeps digestion working smoothly.
Water carries nutrients around the body and removes waste. Drink it steadily through the day rather than waiting to feel thirsty, because thirst arrives only after the body has already begun to run short.
The three main meals are breakfast, lunch and dinner. Skipping breakfast leaves the body without fuel for the longest working part of the day.
4. Traditional Tamil foods
Everyday South Indian food is well built for nutrition.
- Idli and dosa are made from a fermented batter of rice and urad dal. Fermenting increases the vitamins and makes the food easy to digest.
- Sambar brings toor dal for protein together with vegetables such as drumstick, brinjal and pumpkin for vitamins.
- Keerai, the local greens, is rich in iron, which the blood needs.
- Curd helps digestion and supplies both protein and minerals.
A plate of idli with sambar and a portion of keerai already covers four of the five nutrients.
5. A home garden
A thottam at home, even in pots on a terrace, can grow curry leaves, coriander, chillies, tomatoes, brinjal and greens.
The vegetables are fresh, they carry no sprayed chemicals, they cost nothing after the first seeds, and tending them is good exercise.
6. Worked examples
Example 1. A child eats only rice for lunch. Which nutrients are missing, and what could be added?
Protein, vitamins and minerals are missing. Adding sambar or dal supplies protein, and a portion of keerai or a vegetable supplies vitamins and minerals.
Example 2. Which nutrient builds and repairs the body, and name two sources.
Protein. Dal and egg are two sources; milk, fish and paneer are others.
Example 3. Why is a vitamin tablet not a replacement for vegetables?
Real food carries fibre and many other useful substances alongside the vitamins, and a tablet has none of these. A tablet can fill a specific gap but cannot replace a meal.
Example 4. Why is idli described as easy to digest?
Its batter is fermented before cooking. Fermentation begins breaking the food down and also raises its vitamin content.
7. Practice
- Name the five nutrients.
- Which two nutrients give energy?
- Give two sources of protein from a Tamil kitchen.
- What does fibre do, and where does it come from?
- Why should you drink water before you feel thirsty?
- Name the three main meals of the day.
- Give two benefits of growing vegetables at home.
8. Answers
- Carbohydrates, proteins, fats, vitamins and minerals.
- Carbohydrates and fats.
- Dal and egg; milk, fish or paneer would also be correct.
- Fibre keeps digestion working; it comes from vegetables, fruit and whole grains.
- Because thirst only appears after the body has already started to run short of water.
- Breakfast, lunch and dinner.
- The vegetables are fresh and free of sprayed chemicals, and gardening is good exercise.
9. Summary
- Five nutrients: carbohydrates, proteins, fats, vitamins and minerals.
- Carbohydrates and fats give energy, proteins build and repair, vitamins and minerals protect.
- Carbohydrates should not be avoided; a growing child needs that energy.
- A balanced diet has all five nutrients plus fibre and water.
- Drink water through the day, since thirst comes late.
- Idli, sambar, keerai and curd together cover most of what the body needs.
- A home garden gives fresh, chemical-free vegetables and healthy activity.
