How do you make a simple theodolite?

Answer 1

Making a simple theodolite: an activity for a measurement lesson

February 6, 2010

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Tags: 3rd grade, homeschool, math activities, measurement

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A theodolite is a surveying instrument of unknown origin, but can be traced back to the 16th-century English mathematician Leonard Digges. This is info for you not the child.

You will need:

• a piece of thick cardboard
• a plastic straw
• thread, or thin string
• a small screw
• tape
• scissors
• a ruler
• tape measure for activity

Follow these steps to make your theodolite:

1. Cut a 6 x 6 inch square from the cardboard
2. cut the square in half diagonally
3. tape the straw to the diagonally cut edge of one of the triangles
4. cut a 10″ pice of thread, and tie on end to the screw
5. tape the other end of the thread to the triangle so that it hangs straight down along one of the 6″ edges.

Your theodolite is ready to rock & roll. Not really, but is is ready to measure tall things. If you can find a straw as long as the diagonal side, then by all means allow the straw to run the entire length of the side. This was the longest straw I had.

Using your new tool is simple. Follow these easy steps:

1. find a tall object that you would like to measure
2. raise your theodolite up to your eye, and look through the straw.
3. find the top of your object through the straw
4. make sure your string with the screw on the end stays straight along the edge of your triangle.
5. You must move backward or forward until the top of your object can be seen through the straw. The thread must stay in line with the edge of your triangle. It can not dangle forward, backward or to the side.
6. Once you have found the correct position and can see the top of your object through the straw & the string is aligned with the edge of your triangle, mark your position on the ground. You have created an invisible triangle.
7. After you have marked your position on the ground, measure the distance you are from the base of the object you are measuring using the tape measure.
8. Now measure your own height.
9. Add the distance you measured to your height. This is the height of your object.

For instance, if the distance to the tree is 45 feet, and you are 4 feet 10 inches tall, your total would be 49 feet 10 inches.

When we did this activity, we used a tape measure. I had her write down the distance to the object in inches, and her height in inches. After she added the 2 heights together , I had her convert the inches to feet in order to get in some math practice.

So if her total were 495 inches, she would find how many feet this is by dividing by 12. It would be 41 feet, 3 inches.Like

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1. lessons this week-finishing up linear measure « Our Little Nature Nest

   [...] we walked around a bit we sat down by the river, and made a simple cardboard theodolite. A theodolite is a tool surveyors use to measure tall objects from a distance. You can make a very [...]Reply