Graphs, charts and data in geography
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교육자를 위해: Graphs, charts and data in geography(Geography, Geographical Skills)을(를) 위한 바로 쓸 수 있는 수업 슬라이드, 복습 노트 — 수업에 사용하거나, 학습자들이 실시간 게임으로 즐기는 인터랙티브 클래스 활동으로 진행하세요.
수업 노트
Choosing and drawing graphs
- Choose the display to answer the enquiry. Separate bars compare categories; a time-series line connects ordered observations at correctly spaced times; scatter points pair two numerical variables. Use a title, units and an honest linear scale where appropriate. Bar-length comparisons normally start at zero; clearly mark any axis break.
- A histogram groups continuous measurements into adjoining intervals. Specify boundaries without double counting. With equal widths, frequency can be the height; for unequal widths, use frequency density = frequency ÷ class width so area represents frequency. A pie chart or divided bar shows parts of a defined whole; sector angle = category frequency ÷ total × 360°.
- Climate graphs combine monthly precipitation bars (mm) and mean temperature lines (°C), with separate axes and a stated averaging period. Population pyramids compare age bands across recorded sex categories. Check counts versus percentages, denominators and whether the final age band is open-ended.
- Thematic maps encode different information: choropleths shade area classes, isolines join equal values, proportional symbols scale size, dot-density maps represent quantities and flow lines show movement. Use the key and units. Circle areas, rather than radii, should be proportional to magnitudes. Choropleths usually suit rates or densities better than raw totals when areas differ.
Describing and interpreting
- Describe the overall pattern, then support it with figures and units and identify exceptions. In the invented plotted series, population rises from 10 million in 1950 to 20 million in 2000, but falls from 14 to 12 million between 1960 and 1975. It doubles overall without growing steadily throughout.
- Read the scale before estimating. Interpolation estimates within the observed range; extrapolation extends beyond it and may be less defensible if conditions change. Joined points do not mean every intervening value was measured. Compare equivalent periods, definitions and units.
- An anomaly differs from the distribution or expected pattern. Record its values, investigate possible causes and distinguish a supported explanation from speculation. Genuine environmental variation must not be silently removed to improve a trend.
Invented population observations
Calculations
- Mean = sum ÷ count. For 2, 4, 4, 6 and 9, mean = 5, median = 4, mode = 4 and range = 7. Order data before finding the median; with an even count, average the two middle observations. A dataset can have several modes or no unique mode.
- IQR = Q3 − Q1, the spread of the middle half. For the illustrated summary 1, 2, 3, 5, 7 m, IQR = 3 m and range = 6 m. Quartile conventions can differ for small raw datasets; use the one required by the question or board.
- Percentage change = (new − original) ÷ original × 100. Population 20,000 to 25,000 increases by 25%; a count 80 to 60 decreases by 25%. The original is the denominator. A percentage change from an original zero is undefined by this formula.
- A proportion can become a percentage or pie sector. In the invented 30-building survey, 15 shops represent 50% and 180°. For a grouped frequency table, a running cumulative total locates medians or quartiles; estimates within a class need assumptions about its distribution.
Summaries: 2, 4, 4, 6, 9
Statistical ideas
- A scatter graph shows association in paired numerical observations. Describe direction, strength and shape. Positive means values tend to rise together; negative means one tends to fall as the other rises. A curved association can exist even when a straight line is unsuitable. Correlation does not prove causation.
- Random sampling uses chance selection from a defined frame; systematic sampling takes observations at fixed intervals, often after a random start. Stratified sampling selects within defined groups; proportional allocation is one option. Convenience sampling uses accessible cases and risks bias. A bigger sample alone does not remove non-response, excluded groups or systematic measuring faults.
Invented paired river observations
Using secondary data
- Check who produced the data, its purpose, date, geographical coverage, units, definitions, sample and collection method. A respected source still needs to match the enquiry. Comparable independent evidence can support or challenge an interpretation.
- Watch for truncated axes, unequal graphical intervals, unsuitable class boundaries and changing denominators. Area averages conceal local variation. Do not compare counts with percentages or different-length time periods without making an appropriate adjustment.
Worked chart examples
- The equal-width pebble histogram is invented: 4, 8, 6 and 2 pebbles occupy the length intervals 0–2, 2–4, 4–6 and 6–8 cm. The total is 20; the modal class is 2 ≤ length < 4 cm. The adjoining bars represent intervals rather than separate named categories.
- The pie chart’s 15 shops, 10 homes and 5 offices total 30. Their shares are 50%, one third and one sixth; the renderer derives angles 180°, 120° and 60° from those counts. Both examples are teaching datasets, not field observations.
Invented pebble lengths
슬라이드
연습 문제
무료 미리 보기 — 39개 중 8개 문제. 가입하면 전부 볼 수 있어요.
1.What is the mean?
Easy- Athe sum divided by the number of values
- Bthe middle value
- Cthe most common value
- Dthe difference
2.What is the median?
Easy- Athe sum divided by the number of observations
- Bthe most frequent observation
- Cthe maximum minus the minimum
- Dthe middle observation after ordering, or the mean of the two middle observations
3.What is the mode?
Easy- Athe mean
- Bthe range
- Cthe most frequent value
- Dthe middle
4.What is the range?
Easy- Athe total
- Bhighest minus lowest
- Cthe average
- Dthe middle
5.Which graph shows proportions of a whole?
Easy- Apie chart
- Bline graph
- Cscatter graph
- Dhistogram
6.Which graph is usually most suitable for investigating association between paired numerical measurements?
Easy- Apie chart
- Bbar chart
- Cmap
- Dscatter graph
7.What is a climate graph?
Easy- Aa map
- Ba scatter graph
- Cmonthly precipitation bars and a monthly mean temperature line
- Da pie chart
8.What is an isoline map?
Easy- Aa flow map
- Ba map with lines joining points of equal value
- Ca shaded map
- Da dot map
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