☰ Contents · Geography

Using topographic maps, time reckoning and practical work

Lessons 9–11 · 3 lessons · P. Gulomov, H. Vahobov, P. Baratov, M. Mamatqulov. Geography (Physical Geography of Central Asia; Physical Geography of Uzbekistan), Grade 7. Revised and expanded 5th edition. “O‘qituvchi” Publishing House, Tashkent, 2017
11

Practical work

Textbook: p. 30
GoalPractise calculating distances by scale and time differences between time zones.
New words
scale · masshtabtime difference · vaqt farqimeasuring with a ruler · chizg‘ich bilan o‘lchashUTC+5 · UTC+5
Explanation

To find a distance, first measure the gap between two points with a ruler in centimetres. Then read from the scale how many km 1 cm stands for and multiply the two numbers. For example, if 1 cm = 40 km on a map and two cities are 5 cm apart, the real distance is 5 × 40 = 200 km. To find a time difference, write each place’s time zone in UTC and subtract: a place to the east is ahead and one to the west is behind. For example, Tashkent is UTC+5 and Beijing UTC+8; the difference is 3 hours, so when it is 10:00 in Tashkent it is 13:00 in Beijing. Always check the result by calculating backwards once. When you measure from an atlas, ruler error may make the answer differ by 5–10 percent, which is normal.

Worked examples
On a map with 1 cm = 60 km, Tashkent–Samarkand measured 4 cm: 4 × 60 = 240 km (approximate straight-line distance).
Tashkent is UTC+5, London in winter UTC+0: the difference is 5 hours; at 20:00 in Tashkent it is 15:00 in London.
Class activity

“Practical workshop”: each group chooses 3 pairs of cities in the atlas and calculates distance and time difference; another group checks the result by working backwards.

Practice
1
Scale 1 cm = 80 km, two points are 3 cm apart. What is the distance in km?
2
It is 14:00 in Tashkent (UTC+5). What time is it in Beijing (UTC+8)?
3
It is 21:00 in Tashkent (UTC+5). What time is it in Moscow (UTC+3)?
4
Why may a distance taken from an atlas differ from official data? Give two reasons.