Triangulation & Sextant Incline Clinometer Survey
A challenging, hands-on discovery and STEM project designed for curious young minds aged 10 to 14.
Materials Needed
- • 180-degree clear plastic protractor (1 unit)
- • Straight rigid drinking straw (1 unit)
- • Thin nylon string (30 cm)
- • Heavy metal nut or sinker weight (1 unit)
- • Tape measure (15+ meters or pre-measured rope) (1 unit)
- • Notebook, scientific calculator (or phone), pencil (1 set)
Pro Tips
- → Tape the drinking straw across the flat 0-180 baseline edge of the protractor to serve as your sighting scope.
- → Dangle the weighted string from the central origin point; reading the plumb-line angle and subtracting from 90° yields the true sight angle.
- → The formula for object height is: Height = (Distance to Base × tan(Angle)) + Eye Height.
Safety First
Watch footing on outdoor slopes while focusing on the clinometer sights.
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Step-by-Step Instructions
Step 1
Tape a straight drinking straw across the flat diameter edge of a plastic protractor, and suspend a string with a heavy nut from the central hole.
Step 2
Measure a baseline distance of exactly 15 meters away from the base of a tall tree using a measuring tape.
Step 3
Look through the straw sight to the highest point of the tree canopy, and have a partner read the angle where the weighted string crosses the protractor.
Step 4
Calculate the tangent of your sight angle, multiply by the 15 m distance, and add your eye-level height to find the tree's total height.