Bones and Muscles
Objectives

Identify that humans and some other animals have skeletons and muscles for support,
protection and movement.
Plenary
Show the pupils the ‘Bones Song’ from Sesame Street. Do the pupils know the names of any
bones? Why may we need bones?
The functions of bones and muscles
Show the pupils a diagram or a model of an adult human skeleton. Ask the pupils if skeletons
grow. Can they identify the skull, the ribs and the backbone? Can they feel these bones in
their own bodies?
Explain that the skeleton has several functions.
One of its jobs is to protect delicate organs. What body parts do the skull and ribs protect?
Another job is to help us move. Explain that joints are found where bones meet. Our body
can bend at its joints. Muscles are attached to the bones and when they tighten, they become
shorter; pulling up the bone it is attached to. The final important job is to support our bodies.
The backbone helps us to stand or sit up straight. Can the pupils feel their bumpy backbones?
Pupils must note:
Our bones and muscles protect us, support us and help us to move.
Pupils may note:
Muscles are joined to bones. When they tighten, they pull the bone they are attached to, allowing
us to move our skeletons.
The pupils should either draw a picture of what a person may look like without a skeleton or
write a short story about a person who wakes up without a skeleton. They should consider
some of the difficulties that would come from having no skeleton i.e.: organs left
unprotected, inability to stand straight and no joints to help them move.
Animals without skeletons
Pupils should cut out the pictures of animals and sort them into two categories: those with
backbones (vertebrates) and those without backbones (invertebrates).
Now pupils should concentrate on the invertebrates. Some invertebrates have exoskeletons: a
tough coating worn on the outside which protects them. Which of these animals have
exoskeletons? Hint: exoskeletons often look like shells.
© Education Umbrella 2015
Vertebrates: human, shark, crocodile, kakapo parrot, otter, ostrich. Invertebrates with
exoskeletons: lobster, ladybird, stag beetle. Invertebrates without exoskeletons: jellyfish,
earth worm, octopus.
Assign these animals to the pupils. The pupils should decide how to act out the movements of
their animal. Beginning with the vertebrates, then invertebrates with exoskeletons, then
invertebrates without exoskeletons, pupils should demonstrate how their given animals move.
Ask the pupils how movement is different between these three groups. Pupils may be able to
identify that invertebrates without exoskeletons have limited movement and usually float or
wriggle, while having a skeleton or exoskeleton allows for more varied movement.
Pupils may note:
Animals with backbones are called vertebrates. Animals without backbones are called
invertebrates. Invertebrates may have exoskeletons.
Possible extra-curricular questions
How many invertebrates are there?
There are estimated to be 1,300,000 different species of invertebrates. They make up ~97% of
different species on Earth (so all the different mammals, reptiles, amphibians, fish and birds
make up only a tiny fraction of all the species).
Can an exoskeleton fall off?
Yes, and as long as a new exoskeleton has been prepared underneath, it is not damaging.
Many invertebrates shed their exoskeletons when they grow too large for them. They emerge
with a new exoskeleton. This process, called ecdysis, allows some animals to regrow limbs or
repair damaged tissue.
How many bones do we have?
Adults have 206 bones. When you are born, you have 270 bones, but when you grow up, some
of them fuse together. You have 27 bones in each hand.
How many muscles do we have?
Our muscles make up about 1/3 of our body weight. Though it is often said that there are
about 600 muscles in the human body, it is difficult to count because muscles come in all
sizes and can be made up of many layers of tissue.
Which bone is the biggest?
The thigh bone (femur) is the biggest bone in a human. The biggest bones in the animal
kingdom are probably the mandibles (lower jaw parts) of the blue whale, which can reach 6m
long.
© Education Umbrella 2015