• Source of the lake water: Rain that falls on the surrounding hills flows downhill as small streams and collects in the low-lying lake. It may also be fed by underground water (springs) or a nearby river. So the water mainly comes from rainfall running down the hills.
• Who made the road and why: The road was built by people — usually the local government or Public Works Department. It was made so that villagers, vehicles and goods can travel to and from the house/village to nearby markets, schools and other villages.
• The people in the house: They could be farmers, fisherfolk or cattle-keepers. They might farm the land, fish in the lake and fetch water from it. Their history: their ancestors probably settled here because of the water and fertile land. Their future: it depends on rainfall, farming, jobs, education and whether the area develops.

Why this is Social Science: one small picture raises questions of geography (water, landforms), history (the people’s past), and economics (their livelihood) — exactly the subjects Social Science studies. Write your own answers and discuss them with your classmates.

• 1. The hospital is the pink building marked with a red cross (+), near the centre of the map — below the apartments and to the left of the Nagar Panchayat.
• 2. The blue-coloured areas stand for water bodies. On this map they show the lake and the river/stream. Blue is the standard map colour used for water.
• 3. The railway station is on the far left (west) of the map. The school is close to it, the Nagar Panchayat is in the middle, but the public garden is on the far right (east). So the public garden is the farthest from the railway station.

Class activity: In groups, draw a map of your own school with the roads leading to it and a few neighbouring buildings, then compare the maps.

1. Convert real size to paper size using the scale (1 cm = 10 m):
   Length on paper \( = \dfrac{40\text{ m}}{10\text{ m/cm}} = 4\text{ cm}\),   Width on paper \( = \dfrac{30\text{ m}}{10\text{ m/cm}} = 3\text{ cm}\).
2. Find the diagonal on paper using the Pythagoras theorem for the right-angled triangle formed by length, width and diagonal: $$ d = \sqrt{(4)^2 + (3)^2} = \sqrt{16 + 9} = \sqrt{25} = 5\ \text{cm} $$
3. Convert the diagonal back to real length using the scale: $$ \text{Real diagonal} = 5\ \text{cm} \times 10\ \text{m/cm} = 50\ \text{m} $$
4. Check directly with real measurements: \( \sqrt{40^2 + 30^2} = \sqrt{1600+900} = \sqrt{2500} = 50\ \text{m}\ \checkmark\)

Tip: This is the famous 3–4–5 right triangle — sides in the ratio 3 : 4 : 5.

Remember the compass on the map: North is up, East is right, South is down, West is left.

• Incorrect1. The market lies below the hospital, so the market is actually south of the hospital — not north.
• Correct2. The museum is to the lower-right of the bank, i.e. southeast of the bank. ✓
• Correct3. The railway station is to the left and a little above the hospital, i.e. northwest of it. ✓
• Incorrect4. The lake lies to the left and below the apartments, i.e. to the south-west/west of the apartment blocks — not northwest.

Also try: Taking your school as the starting point, work out roughly in which cardinal direction your home lies, and discuss it with your teacher and parents.

• Start by drawing your home and school, then add the roads that connect them.
• Add landmarks: temple/mosque/church, a pond or river, a park, shops, a bus stop, a post office.
• Put a North arrow (N) in a corner so directions are clear.
• Use standard symbols (from Fig. 1.2) — e.g. a line for a road, wavy blue for a river, ‘PO’ for a post office, tree symbols for a garden.
• Keep the relative positions roughly correct; it need not be to exact scale.

Black’s queen’s pawn sits on d7. To mirror White’s move, Black pushes that same pawn two squares forward:

Just like the shop “7^th shop, 5^th row” example, each square is fixed by two coordinates — a letter (column, a–h) and a number (row, 1–8). That is exactly how latitude and longitude fix a place on Earth.

• Mumbai — about 19°N latitude, 73°E longitude
• Kolkata — about 22°N latitude, 88°E longitude
• Singapore — about 1°N latitude, 104°E longitude (it lies almost on the Equator)
• Paris — about 49°N latitude, 2°E longitude

Note: These are rounded values read off a globe/atlas. Your exact readings may differ by a degree or two, which is fine.

Why: The Earth spins from west to east. Because of this, places in the east see the Sun rise and set earlier than places in the west. Tinsukia (Assam) is in India’s far east, while Porbandar (Gujarat) is in the far west. So the Sun sets earlier in Assam — it is already dark there while it is still daylight in Gujarat.

1. The Earth turns 360° in 24 hours, so it turns \( \dfrac{360^\circ}{24} = 15^\circ \) per hour.
2. Longitude difference between the two cities \(= 30^\circ\).
3. Time difference \( = \dfrac{30^\circ}{15^\circ/\text{hour}} = 2 \text{ hours}. \)

Another way: \(1^\circ\) of longitude = 4 minutes of time, so \(30^\circ \times 4 = 120\) min = 2 hours.

• Local time is set by the Sun over a particular longitude. Since Porbandar and Tinsukia are on different longitudes, their local times differ by about 2 hours — noon happens earlier in Assam.
• Standard time is one common time chosen for the whole country, based on a single central meridian. So even though their local times differ, both friends set their watches to the same Indian Standard Time (IST). This avoids the confusion of using many different local times inside one country.