| Purpose: |
To provide experience using the principles of similar
triangles, To practice estimating distances. |
| Season: |
All |
| Materials: |
Three stakes, hammer, paper, pencil, clipboard, string
(optional) |
| TEKS: |
4.1A 4.2A,B,C,D 4.4A,B |
| Background experience: |
- Discuss the characteristics of similar triangles. Remind them that similar and congruent
are not the same.
- On the playground at school, have students choose a position for point A. Drive a stake
in the ground or have a child stand at Point A.
- Place another stake or child at Point B exactly opposite Point A.
- At right angles to AB, measure (or pace ) 10 feet to Point C. Place a marker here.
- Continue walking in the same line for another 5 feet (1/2 of BC); at this spot place
another marker, Point D.
- At D, turn and walk away, but at right angle to line DB and walk to a point where marker
C is in a straight line with Point A and stop. This is point E. DE is half the length of
AB. Measure this distance and double it to determine the full distance of AB.
- Check by measuring the distance of AB.
- (You might want to use a string between points to help children visualize right angles.)
|
| Procedure: |
- Have students identify Point A as an object (tree, rock, etc.) on the other side of
Green Pool or the canyon.
- Place a stake at Point B on the bank exactly opposite.
- Continue the process as you practiced on the playground.
|
| Questions: |
- Why would you need to know the distance across a body of water or a canyon?
- Would the time of year affect the distance across?
|