What it shows
The globe shows how the Earth is a sphere, with latitudes parallel to the equator and longitudes running pole to pole. A place can be located by its two numbers.
The science
Latitude is the angle north or south of the equator, from 0 to 90 degrees. Longitude is the angle east or west of the prime meridian at Greenwich, from 0 to 180 degrees. Together they give an exact location. The Earth is tilted by about 23.5 degrees, so the axis of the globe is slanted, which is the reason for seasons. The Tropic of Cancer passes through India.
Materials
Cost: under Rs 50. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- A large balloon
- Old newspaper torn into strips
- Flour paste (flour and water)
- Poster paints
- A thread and a marker
- A stand made of a cardboard ring
- A small string loop
Safety
For this project: Wash your hands after using paste. An adult must handle any pins for the axis.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
All the safety rulesStep by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Blow up the balloon and tie it.
Dip the newspaper strips in the paste and cover the balloon with four layers, drying each overnight.
When completely dry, pop the balloon and trim the opening with an adult.
Paint the oceans blue and the continents in green and brown from an atlas.
Mark the equator with a thread and draw it in red.
Draw latitudes every 30 degrees and longitudes every 30 degrees.
Mark the Tropic of Cancer and the prime meridian and your home town.
Tilt the globe in the stand at about 23.5 degrees and fix it.
What you should see
A globe with a correct grid, so you can read the coordinates of Delhi, Chennai or your own town.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1What is the equator?
The zero-degree line of latitude.
2Which line passes through India?
The Tropic of Cancer.
3What is the prime meridian?
The zero-degree line of longitude through Greenwich.
4Why is the globe tilted?
The Earth’s axis is tilted at about 23.5 degrees.
Take it further
Use a torch to show how the tilt makes day length change.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
Free ebooks for this project
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