Lab 1: Growth & Development Lab
Name:_________________________________________Score:____________
In this lab, you will 1) gain experience in interpreting graphs of developmental
data, 2) the opportunity of plot a velocity of curve for height and for weight, and 3)
estimate one’s skeletal maturation by comparing hand and wrist X rays.
Interpreting graphs of developmental data
Most development involves age-related changes that can be graphed over an age
period. The horizontal axis represents the age or time and vertical axis the
measurement being studied. In the graph, one can look across the horizontal axis
and you can view how the measurement has changed over the age period or time.
In graphing developmental data, one needs to keep in mind the type of measure and
the age period. The lower numbers start at left on the horizontal axis and at the
bottom on the vertical axis. The results are usually graphed as a line or bars. If you
are graphing more than one variable, separate colored bars or different types of
lines are used.
Consider Table 1. It contains the mean height in centimeters of a group of children
for every year staring with their 4th birthday and ending with their 9th. This would
be what is called in chapter 1 of our Motor Development Text as “longitudinal data.”
Enter the values and age categories of Table 1 then develop a line graph using your
computer.
Table 1
Age
Height
4
107
5
114
6
122
7
127
8
131
9
137
Let assume that you have just plotted average height for a group of children that
attends public schools in North America and a researcher in England sends you the
average height measurements fro a group of England children. These average
heights are in table 2. Plot the average on the same graph as before. Cut and paste
the graph into the word document that includes your answers to the lab questions.
Table 2
Age
Height
4
103
5
110
6
118
7
126
8
133
9
140
Consider table 3. It contains average scores in centimeters on the “sit and reach”
flexibility test for four groups of boys. It also contains the average scores for four
groups of girls. Let say there is a strong cohort effect, such as the younger two
groups’ have a teacher who led daily stretching exercises. Plot a graph by the
1
various age groups for the sit and reach measure by gender using your software
program. Cut and paste the graph into the word document that includes your
answers to the lab questions.
Table 3
Age
15
Sit & Reach (B) 34.3
Sit & Reach (G) 39.1
16
35.8
41.9
17
33.6
38.1
18
33.6
37.9
Lab questions
1. Examine the first line (table 1) that you plotted on your graph. What does it
tell you about height between 4 and 9 years of age in this group of children.
2. What does the graph tell you about the growth height of the England
children? Compare the growth in height of the North American and England
Children as shown by the graph (remember, these are not real data). Write
out a year-by-year narrative that compares the two groups.
3. What does the bar graph tell you about age related trends in flexibility?
About these trends in boys versus in girls?
4. Does there appear to be a cohort effect (rather than a developmental change)
in the two youngest groups? Describe what you see the graph and explain
your answer.
Graphing a Velocity Curve
In the prior exercise you charted growth, we think of as a distance curve. A distance
curve is where you plot the child’s height and weight at each birthday. From each
graph we could see how far (distance) a child has grown at any age. If the line is flat,
there is not growth. If the slope of the line is steep, the rate of growth or decline in
growth is rapid.
If we want to picture the rate of growth, we can take the change in growth from a
distance curve and generate what is called a velocity curve, which plots speed or
rate of growth against age. A velocity curve can be developed from any distance
measure. The purpose of velocity curves is to identify any growth landmarks.
Velocity curves will include peaks and valleys. A velocity curve enables us to
identify the age at which the growth was the fastest (age of peak velocity). It is
interesting to compare age at peak velocity between genders and other variables for
various growth measures.
Table 4 gives the height (in cm) attained by a boy and a girl on each of their
birthdays from 4 to 20 years of age. Plot a distance curve for the child your
professor assigns, making sure height is on the vertical axis and age is on the
horizontal axis. Graph these data with a computer software program such as Excel.
Cut and paste this graph into your work document that includes your written
answers to the lab questions associated to graphing a velocity curve.
2
Table 4
Age
4
5
6
B
105
111
G
Age
B
G
98
15
176
157
104
16
179
158
7
9
10
126 130 130
137
111
17
181
158
128
20
183
159
117
18
182
159
8
123
19
183
159
11
12
13
14
143 148
156
164
171
133 138
145
152
156
For these height data, complete the table 5, showing the change in height from one
birthday to the next. When you have completed this table, plot a velocity curve.
The common practice is to plot the change at the midpoint of the age period. In this
case, you would plot the change from 4 to 5 (6 cm) at 4.5 years. Cut and paste the
graph into the word document that includes your answers to the lab questions.
Table 5
4-5
5-6
6-7
7-8
8-9
Interval 1516
Change
1617
1718
1819
1920
Interval
Change
9-10 10 11
1112
1213
1314
1415
Lab Questions
5. Look at your height distance curve. Can you see points of apparent transition
from a period of faster growth (where the curve is steep) to a period of
slower growth (where the curve goes up gradually)? What about transitions
from a period of a slower growth to a period of faster growth or inflection
point? What are the ages of the child at the inflection points you identified?
Developmentalists often use the term “age at takeoff” for the age at an
inflection point marks a transition from slower to faster growth. What would
the age at takeoff for any such inflection point for this child?
6. Look at your velocity curve. Is the rate of growth faster at younger ages or
older ages? What is the basis for your answer? Do you see peaks and valleys
in your velocity curve? At what ages? What do the velocity curves show
when then distance curve plateau?
7. Look at the most pronounced peaks on your velocity curves. Look at the
distance curves around the age corresponding to the peak height velocity and
3
the peak weight velocity. What is the characteristic of the distance curves at
these points?
Estimating Skeletal Age
Physiological maturation is more difficult to measure than physical growth. It is
harder to see the biochemical and structural changes of the body’s cells, organs, and
systems. Error is often about physiological maturation solely on the basis of age or
size. Skeletal maturation is a component of physiological maturation that can be
used at any time in the growth period to estimate overall physiological maturation.
The most common sites are the wrist and hand. Wrist and hand is used because we
have established standards published (A Radiographic Standard of Reference for the
Growing Hand) by S.I. Pyle that contains many X rays for various ages throughout a
growth period. When you compare the X rays look at the roundish of the carpal
bones of the wrist, the epiphyseal growth plates of the long bones of the hand and
fingers, and the epiphyseal growth plates of the forearm bones to determine one’s
physiological maturation.
The professor will assign you to study the X ray of the hand and wrist in either
example A or example B. Compare the X ray to those in your textbook (Figures 6-25
and 6-27, pages 163-4). Note the number of wrist bones (carpals), ossified, the
extent of their ossification, and the extent of the ossification at the epiphyseal
growth plates located at the end of the long bones of the hand(metacarpals and
phalanges) and forearm (radius and ulna). The extent of ossification at an
epiphyseal growth plate is typically seen by how complete the end of the bone is
ossified. The epiphysis seen as being larger and as having more of an eventual adult
shape is considered to be more mature.
Example A
Example B
4
As you compare the X ray in this lab with the textbook’s X ray, record the results of
your comparison in Table 6. Enter “M” if the number of ossification centers is more
than the standard, “L” if less, and “S” if the same.
Table 7
Criteria
Number of Wristbones
(carpal) ossified
Extent of wristbone
ossification
Growth plate at distal end
of radius
Growth plate at distal end
of ulna
Growth plates at distal
end of metacarpal (hand)
Growth plates of the
phalanges (fingers)
Textbook Figure 6-25
Textbook Figure 6-27
Lab Questions:
8. From your assessment as recorded in Table 6, is the child whose X ray your
evaluated more or less physiologically mature than pictured in textbook
figure 6-25? Than pictured in textbook figure 6-27?
9. Figure 6-25 in the textbook shows the skeletal age for a boy to be 36 months
of age. Figure 6-26 in the textbook shows the skeletal age for a boy to be 60
months of age. Figure 6-27 in the textbook show the skeletal age for a boy to
be 14 years old. Based on your comparison you did and reported in table 7
and assuming that your X ray is for a boy, what would you estimate the
skeletal age of your child to be? On what do you base your estimate?
10. Assuming that the age of your boy’s X ray is 78 months. Compare this to the
skeletal age you estimated in answer 9. Is your child an early maturer,
average, or late maturer? On what do you base your answer?
5