This study investigated the relationship between a person's height and arm span by measuring 20 subjects between 9-11 years old. The hypothesis was that a person's height would be greater than their arm span. The results found that for most subjects (75%) their height was greater, but for 1 subject (5%) their arm span was greater. On average, heights were approximately 5cm greater than arm spans. The conclusion is that for most children aged 9-11, height is greater than arm span.

1. Length Investigation
Aim:
To investigate the relationship between a person’s arm span and their height.
Hypothesis:
We predict that a person’s height is greater than their arm span.
Materials:
measuring tapes
paper
clipboard
pencils
20 people
Method:
1. Ask someone to lie down on the floor.
2. Make sure their legs are straight.
3. Place the 0 of the measuring tape at the top of the person’s head.
4. Pull the measuring tape down to the person’s feet.
5. Record the number of centimeters on the measuring tape. This is the person’s
height.
6. Ask the person to hold their arms out at right angles (90 degrees) to their
body.
7. Make sure their arms are straight.
8. Place the 0 of the measuring tape at end of their middle finger of one hand.
9. Pull the measuring tape across the person’s body.
10. Record the number of centimeters on the measuring tape at the end of the
middle finger of their other hand. This is the person’s arm span.
11. Check your measurements twice on each person.
12. Repeat the measurements for 19 more people.
13. Record your measurements in a table.

2. Results:
Name Height Arm Span Difference
Yen Yen 140cm 120cm + 20cm
Ki Joo 152cm 152cm 0cm
Simon 145.3cm 141cm +4.3cm
Justus 147cm 137cm +10cm
Aighar 136cm 136cm 0cm
Dennis 134cm 130cm +4cm
Grace 137cm 137cm 0cm
Hena 146cm 137cm +9cm
Xella 138cm 136cm +2cm
Qiqi 150cm 150cm 0cm
Naina 134cm 124cm +10cm
Sang Woo 142.5cm 140.5cm +2cm
Jake 146cm 144.5cm +1.5cm
SeokChae 149cm 138cm +11cm
Takumi 150cm 140cm +10cm
Genjiro 145cm 138cm +7cm
Adam 123cm 122cm +1cm
Syakir 130cm 124cm +6cm
Jae Seo 135cm 146cm -11cm
Krishna 135cm 124cm +11cm
Total 97.8cm
difference
Average 4.89cm
difference
4 out of 20 people’s heights are exactly equal to their arm span.This means they are
shaped like a square. This is 1/5 or 20% of the people measured.
1 person’s arm span was longer than his height. This means he is shaped like a wide
rectangle. This is 1/20 or 5% of the people measured.
15 out 20 people’s height was longer than their arm span. This means they are
shaped like a long rectangle. This is ¾ or 75% of the people measured.
On average, people’s height was 4.89cm (approximately 5cm) greater than their arm span.
Conclusion:
We conclude that at 9-11 years of age, most children’s height is greater than their
arm span.

3. Discussion:
Our sample size was only 20 people. We would need to measure more people to be sure of
the percentage of square and rectangular shaped people in the world.
We had some difficulties getting accurate measurements. We found it hard to decide
whether people should be wearing shoes or not. Some people were measured in shoes,
others in socks. This would change the result by up to 2cm. We also found it hard to keep
the measuring tape straight. Sometimes the tape was bent, which could have made our
measurements less accurate. Also, some people were taller than the length of the tape. We
had to add two measurements together, which could have caused little errors.
We are interested to know if people’s shape changes as they grow. It would be interesting
to repeat this investigation onbabies, younger children, teenagers and adults. That would
help us to understand the percentage of square and rectangular people in the world.
Are you a square or a rectangle?