by john foster and cheryl rumbaugh presentation 09... · protractor measuring angles step 1 place...
TRANSCRIPT
Protractor constructing angles
Step 1
Use the baseline of the protractor to draw one ray of the angle.
Mark
the vertex.
Step 2.
Place the protractor on the ray so that the center is over the vertex of
the angle to be drawn.
Step 3
On the scale of the protractor, find the number of degrees for the
angle to be drawn. Make a mark (point) next to the number of
degrees.
Step 4
Use the baseline of the protractor to connect the point and the vertex
of the angle.
Step 5
Draw a ray from the vertex to the point.
Protractor measuring angles
Step 1
Place the protractor on the angle to be measured so that the
center is over the vertex of the angle and the base line is over
on
the ray of the angle.
Step 2
Make sure that the second ray of the angle crosses the scale of
the protractor. You may need to make the second ray longer.
Step 3
Read the number of degrees in the angle where the second ray
of the angle crosses the scale.
If the first ray extends to the right of the vertex, then use the
inside scale. If the first ray points left, then use the outside
scale.
Using a Standard ruler
Inches are broken into fractions
Teach students equivalent fractions
2/16 = 1/8
4/16= ¼
6/16 = 3/8
8/16 = 4/8 = ½
10/16 = 5/8
12/16 = 6/8 = ¾
14/16 = 7/8
16/16 = 8/8 = 4/4 =2/2 =1
Teach students to identify whether the ruler is marked in
eighths or sixteenths
Practice measuring often
Reading a Standard ruler
Each inch can be broken into parts
Teach students to recognize each part
1/16
½1/4 3/41/8 3/8 5/8 7/8
1/16 3/16 5/16 7/16 9/16 11/16 13/16 15/16
1
Unit conversions
The rules:
To change from a larger unit to a smaller unit multiply by the
conversion factor.
2 feet = _________ inches
Conversion factor
1 foot = 12 inches
2 feet x 12 = 24 inches
To change from a smaller unit to a larger unit divide by the
conversion factor.
12 quarts = ________ gallons
Conversion factor
4 quarts = 1 gallon
12 quarts / 4 = 3 gallons
The ratio or proportion method
a/b = c/d
a x d = b x c
12 quarts =___pints
1 qt = 12 qt
2 pt N pt
1*N=2*12
N=24
12 quarts = 24 pints
Use a formula for conversion
Convert ‐
Celsius to Fahrenheit
F = 9/5 X C+32
Convert ‐
Fahrenheit to Celsius
C=5/9 X (F‐32)
Changing Metric units
To change from one metric unit to another, we
multiply or divide by 10, 100, or 1,000. These conversion factors are all powers of 10. We can move
the decimal point to the right when multiplying and to the left when dividing.
Examples: To change meters to centimeters, multiply
by 100 or move the decimal point 2 places to the right.
5.2 m = 520 cm
To change centimeters to meters, divide by 100 or
move the decimal point 2 places to the left.
520 cm = 5.20 m