6
STEM
Curriculum
Science
Technology
Mathematics
Engineering
Integrated
101
Science Application
Chemical Symbols
There are just over 100 known substances, or elements, in the
world. An
element
is the simplest form of matter and is made up of
only one kind of atom or molecule. Each element is given a chemical
symbol of one or two letters. Chemists, scientists, and technologists
throughout the world use the same symbols, so there is never any need
for translation.
For example, the letter H is the symbol for hydrogen, and the
letter O is used for oxygen. These substances cannot be separated
compounds
Science Activity
STEM
Curriculum
Science
Technology
Mathematics
Engineering
Integrated
55
Technology Application
Art, Nature, and Technology
The shapes and patterns of technological designs are often inspired
by nature. Many patterns are based on shapes that we know quite well:
leaves, flowers, birds, and animals. If you look around, you may find
examples of sunflower tiles on a floor, leaf patterns on a carpet, sofas
and fabrics decorated with wild grasses, or a necklace of ivory pieces,
each carved in the shape of a bird. Usually, the patterns are not exact
copies, but abstract versions that were inspired by the objects. For
example, the design for the faucet shown below may have been inspired
Technology Activity
i to smaller substances, but they can be combined into chemical
182
STEM
Curriculum
Science
Technology
Mathematics
Engineering
Integrated
Engineering Application
Testing Truss Strength
The various designs of trussed bridges are named after the engineers
who first designed them. James Warren, an engineer, patented the first
bridge that used equilateral triangles in 1848. An
equilateral triangle is e
one in which all sides are the same length and all angles are the same.
Today we use trusses more often in roofs of buildings than for bridges,
but the reasons for using them are the same. They span distances of
10 to 100 feet (3 to 30 meters) using a minimum amount of material
while providing the maximum amount of strength.
Engineering Activity
b a tree similar to the one shown.
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146
STEM
Curriculum
Science
Technology
Mathematics
Engineering
Integrated
50 × 1
3
4
Problem
statement:
50 7
1 4
×
Convert to
improper
fractions:
Multiply:
50 7
1 4
× =
50 7
=
350
1 4
= 4
×
×
Divide: 350 ÷ 4 = 87, with a remainder of 2
Reduce: 87
2
4
1
2
= 87
A
Math Application
Using Mixed Fractions to Calculate Material
Needed
Before manufacturers begin shaping materials, they have to decide
how much material will be needed for a given production run. For
example, a manufacturer of metal nameplates must determine how
many nameplates can be made per linear foot of metal. This often
involves working with mixed fractions. A
mixed fraction
is a number that
includes both a whole number and a fraction, such as 1change
1£2.
1
£ £
To multiply a whole number by a mixed fraction, first the mixed
number to an improper fraction. To create an
improper fraction
, multiply
the whole number part of a mixed fraction by the denominator of
fraction and add the result to the numerator. Place this number over
denominator to complete the fraction. For example, to convert
3×£22tothe6;=the1
1
£ £
an
improper fraction, multiply 3 by 2 and add the result to the 1: 3
6 + 1 = 7. The improper fraction is written as
7£2.
7
£ £
After you have created the improper fractions,
multiply the numerators. Then multiply the denominators.
Reduce the result to lowest terms. Finally, divide the
denominator into the numerator to reduce the fraction
to a mixed fraction. For example, suppose the manufacturer has
an order for 50 copper nameplates. Each nameplate
will be
71£2†
1
£ £
× 13£4†
† 3
£ £
. If the nameplates are blanked
(stamped out) of a roll of copper that is exactly
71£2†
1
£ £
wide, what length of copper will be needed?
†
(Note: The improper fraction for any whole number
is that number over a denominator of 1.)
Math Activity
A door manufacturer needs 150 door strikes (Figure A) measuring
21£4†
1 £ £
×
13£4†
† 3
£ £
. These will be blanked from a roll of brass, using the most
economical cutting pattern. A space of 1£8†
1
£ £
is needed between each
†
piece. See Figure B for examples of cutting patterns. Determine the
length of brass needed if the roll of brass is:
A. 2†
wide
†
B.
21£2†
1 £ £
wide
†
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