Look at (an) animal(s) and discuss their features and needs
Start with discussion of how living things stay alive:
We are living, because we breathe, eat, reproduce (have babies). Every living thing needs to breathe (or get oxygen from the air), needs food for energy (different kinds) and water, and a place to shelter (a home).
Show the tree of life poster:
All these living things need these same things to survive. What living things do you see? (And discuss how each one breathes, eats etc.)
Look at one or more of the following animals closely:
Hand out a wood bug in a dish to each student and ask them to use their magnifier to look at them closely.
Ask many legs does it have; can they see its eyes on the side of its head? Discuss how they get air from gills (like a fish) and other features that allow them to stay alive.
Look at wood bug images (projected large if possible) to see the gills and other features, and a wood bug with babies.
Return wood bugs to a classroom habitat, checking that the habitat has all the needs of the wood bugs (food, water, air, shelter). Optionally keep the habitat in the classroom. Or release the wood bugs outside into their habitat.
Not all animals have legs. Can you think of some?
Hand out a worm in a dish to each student.
There’s an animal on your desks that does not have legs.
Tell me what else you notice about it. How is it different from us? How is it the same? How is it different from a wood bug? How is it the same?
Discussion: if it has no legs - how does it move? Contract your muscles to make yourself move.
Worms only have primitive eyes, enough to sense light and dark. Cover yours to see like a worm.
Return worms to a habitat (e.g. indoor worm compost bin) where they have food and water.
Tree of life
Find worms on the tree of life and/or find wood bugs (or where wood bugs would be - they're not on the poster).
These are animals without bones.
Look at all the other animals that do have bones.
Look at skulls of a prey and predator animal.
Using a number line to sort animals by number of legs
There are a huge variety of animals - show the tree of life poster. We can start to understand this variety by looking at one characteristic: legs on animals.
Lay out the number lines for students.
Hand out wood bugs, worms, and other animal images/point to other real animals in the room.
Look at the worms and wood bugs with a magnifier.
Ask students to put each animal or picture next to the number of legs it has. If you are not sure, don’t guess - look closely and you might have a better idea of the answer. Scientists often look closely to learn more about something.
Listen to an audio recording of a horse galloping and walking. These are sounds of an animal that moves with four legs.
Other animals with 4 legs can do this too - you may have seen dogs doing it.
Using a Venn diagram to sort animals by their features
Make overlapping circles with string, or draw them on a large piece of paper.
Hand out wood bugs, worms, and other animal images/point to other real animals in the room.
Ask students to sort the animals into the Venn diagram by whether they have legs or not, and whether they have bones or not.
Students should look closely at the living things with magnifiers to see if they have legs. Students will not be able to see if they have bones or not, but use discussion about how squishy the animals are to help them figure out if they have bones. Wood bugs do not have bones, but a hard shell (exoskeleton) to protect them.
Possibly add a third circle to the Venn diagram - whether the animals have eyes or not.
Discussion after Venn diagrams are complete:
Even though some animals have legs and some don’t they can all move. They move using their muscles. For the animals that have bones, the muscles work by pulling on the bones.
Look closely at each of the animals to see how they move with and without legs or bones.
Possible animals to include:
Wood bug: legs, no bones. Muscles lift legs up one at a time and push the ground.
Worm: no legs, no bones. Muscles contract and expand to make the worm stretch. Bristles.
Snake: no legs, bones. Muscles attached to the bones bend the body and grip the surface.
Person: muscles connect to the bones. When the muscles contract the leg lifts up.
Horse: legs and bones, like us, but they have 4 legs.
