1. Length Investigation
Aim: To investigate the relationship between head circumference and arm length.
Hypothesis: We predict that Grade4 students’ arm will be greater than their head.
Materials:
1 measuring tape
1 pencil
1 eraser
1 sheet of paper
1 clipboard
15 Grade4 students
Method:
1. Collect your materials.
2. Draw a table with 4 columns (name, arm length, head circumference and
difference).
3. Ask someone not to move his/her head.
4. Put the 0cm of the measuring tape at the head.
5. Pull the measuring tape up until it turns one time.
6. Record the number of centimeters shown on the measuring tape. This is the
person’s head circumference.
7. Ask same person to hold out their arm.
8. Put the 0cm of the measuring tape at the end of the shoulder of the same arm.
9. Pull the measuring tape across the person’s body to the end of the shoulder.
10. Record the number of centimeters shown on the measuring tape. This is the
person’s arm span.
11. Repeat the measurements for the other 14 students.
12. Record these measurements under the headings of head and arm span.
Results:
Name: Arm (cm) Head (cm) Difference (cm)
Sarthack 42 51 +9
Jack 50 56 +6
Joshua 35 54 +19
Geon woo 39 54 +15
Sajid 44 54 +10
Annie 44 53 +9
Kaopoon 42 51 +9
Kazuki 48 56 +6
Jermaine 50 54 +4
Diana 38 54 +16

2. Hyun seo 38 56 +18
Hanson 48 53 +5
Benedict 45 55 +10
Kota 41 53 +12
Na Youn 37 49 +12
All the people in grade4, their heads are bigger than their arm length (100%).
No one’s arm length is greater than his or her head (0%).
On average, people’s head circumference is 11cm greater than their arm length.
Conclusion:
Our hypothesis was wrong. All the Grade4 students’ head circumferences are
greater than their arm lengths.
Discussion:
Our sample size was only fifteen 9-10 year olds. They came from a variety of
backgrounds. We would need to measure more 9 years olds to be sure of the
relationship between arm length and head circumference in the students around the
world.
We had some difficulties getting accurate measurements. Some people measured in
different ways and didn’t always start at the zero on the tape. We also found it hard to
keep the measuring tape straight, which could have made our measurements less
accurate.
We would be interested in knowing how people’s head is greater than their arm
length. It would be interested to repeat this investigation on babies, young children,
teenagers and adults. This would help us to understand the people’s heads and arm
length better.