Where a Bone Gets Longer: teacher key

How You Grow, grade 7 edition, written for 7th grade. Your bones grow at their ends, inside plates of rubbery cartilage that slowly turn to bone. Sleep, food, movement and your genes all play a part in how that happens.

Read the book. Print this page for the key.

Questions and answers

1. Where does a long bone grow longer?
   • In the middle
   • At each end, next to a growth plate (answer)
   • Only on the outside
2. What makes the collagen framework of bone hard?
   • Calcium phosphate (answer)
   • Cartilage
   • Vitamin D
3. Why does the bone you build as a kid matter for life?
   • Bones stop changing at age 2
   • The most bone you will ever have is built when you are young (answer)
   • Kids never lose any bone
4. What does the word cartilage mean?
   • A rubbery, flexible material (answer)
   • A kind of vitamin
   • A bone in the leg
5. Why do girls and boys have separate growth charts?
   • They grow in different patterns and at different rates (answer)
   • Their bones are made of different minerals
   • Charts are too long for one
6. What does a baby average in its first year?
   • It grows about 10 inches longer (answer)
   • It does not grow at all
   • It grows about 60 inches longer

Words

• cartilage: rubbery body material
• collagen: bone framework protein
• calcium: bone-building mineral
• stadiometer: height measurer