Femur Bone: Height of Animal

(Image: Skeletal image of an elephant with emphasis highlighted of where its femur is located.)

Objective:

  1. Measure and compare femur length to animal height in a personal scenario.
  2. Use this ratio to determine the height of unknown species from a variety of femurs.

Prerequisite Knowledge:

NSTA Science Process Skills:

  • Observe:
  • Measure:
  • Infer:
  • Sort:
  • Predict:
  • Communicate:

Accessibility:(Specific changes to procedure in blue and in square brackets)

What You Need:

  • Femurs, various lengths, sold as dog treats or ask a butcher for leftovers:
  • Pork femur - 1
  • Cow femur - 1
  • Lamb femur - 1
  • Buffalo femur - 1
  • Human femur model – 1
  • Measuring tape, 12 ft. capacity – 1 per bone
  • Sharpie marker, for labeling bones – 1
  • Calculators – 1 per

Preparation:

  • Set out the femurs as 1 femur per station. Remove any labeling so that the animal type is a mystery. Label the bones and create a key for yourself.

What You Do:

  1. Ask, “How do scientists know how tall the dinosaurs were?” (bones) “How do they know that?” (Answers vary)
  2. Explain, “Scientists use bones and heights of present day animals to calculate the height of prehistoric animals. They calculate the ratio of bones to height and use that ratio for dinosaur bones.”
  3. Tell, “We’re going to do the same thing. We will use our own bones to make the ratio, then we’ll use that ratio for these other bones I have here.”
  4. Group the students into pairs by some expedient means. Direct students to measure their partner’s height and record the data in inches only.
  5. Perform a calculation on the board showing how to multiply the feet by 12 then add the remaining inches for your own height. Direct students to do the same for their height.
  6. Direct students to measure the length of their own femur, then convert it into inches as before.
  7. Measure your own femur, convert the amount into inches, and then write the result on the board.
  8. Calculate the ratio by dividing your height by your femur length on the board. Round the result to the hundredths place. Direct students to do the same. Note: the result should be close to 4.
  9. Ask, “What was your ratio?” Record student results on the board.
  10. Ask, “Are these numbers pretty close?” (Yes)
  11. Explain, “The ratio of height to femur length is pretty close for most animals. In humans and animals it differs slightly, but is relatively conserved. You are going to use your ratio to calculate the heights of the other animals I have here. To do it, measure the femur length, and then multiply by the ratio you calculated.”
  12. Direct students to go to each table and measure the femur’s length. Each student should then multiply by the ratio they calculated earlier.
  13. Ask for each bone, “How tall was this creature?”

14. Show students the femur lengths for dinosaurs and an elephant.

-Apatosaurus - 96 inches

-Elephant – 45 inches

-Diplodocus – 72 inches

-Allosaurus – 14 inches

15. Ask students to use their ratios and calculate the heights for these animals.

Student Questions:

Students should show their sets of calculations on the back of the paper and find the height of each of the bones.

Differentiations:

  1. Bones and height. Bones are used to determine the height of humans in forensic situations. Using the length of a bone found at a burial, height can be calculated.
  2. for men
  3. for women

Present the students with a mystery bone and ask them to determine the age of its owner.

  1. Use average data. Average the student data, including your own ratio, to generate one class ratio that everyone uses. This simplifies grading.
  1. Anthropometry and biomechanics is a wide field. Other ratios than femur to height exist with varying degrees of accuracy. Students could determine other ratios and see if they were better indicators of height. Toe length, shin length, thumb, forearm, head size, etc.

NGSSAlignment:

2-LS4-1; 3-LS4-1; 4-LS1-1

CCSSAlignment:

W.2.7; W.2.8; MP.2; MP.4; MP.5; 3.MD.B.4