Glossary: Terms Starting with O
32 definitions in Science with links to the lessons that teach each word.
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object
ScienceFrom Grade 1
a thing that you can see or touch
Learn it in: Identifying objects (Grade 1), What are materials (Grade 1)
observation
ScienceFrom Grade 2
something you notice using your senses or a tool
Learn it in: Reviewing scientific observation (Grade 2)
observe
ScienceFrom Grade 1
to look and use your senses to find out
Learn it in: Using our senses to observe (Grade 1), What is weather (Grade 1), Observing the sky (Grade 1)
omnivore
ScienceFrom Grade 1
an animal that eats plants and animals
Learn it in: Animal food (Grade 1), Consumers (Grade 3), Consumers (Grade 5)
once living
ScienceFrom Grade 1
alive before, but not alive now
Learn it in: Living and non-living things (Grade 1)
opaque
ScienceFrom Grade 1
not letting light through
Learn it in: Shadows (Grade 1), Light and shadows (Grade 2), Transparent and opaque materials (Grade 2)
open circuit
ScienceFrom Grade 4
a loop with a gap, so no current
Learn it in: Open and closed circuits (Grade 4), Simple circuits (Grade 6)
opinion
ScienceFrom Grade 5
what someone thinks or feels, not measured
Learn it in: Scientific investigation questions (Grade 5)
optimise
ScienceFrom Grade 5
to make as good as possible
Learn it in: Engineering improvements (Grade 5), Improving designs (Grade 6)
orbit
ScienceFrom Grade 4
the path around another object
Learn it in: Earth as a planet (Grade 4), Planets (Grade 5), Earth’s revolution (Grade 5)
orbital period
ScienceFrom Grade 6
the time to complete one orbit
Learn it in: Planetary motion (Grade 6)
organ
ScienceFrom Grade 3
a body part with a special job
Learn it in: Major internal organs (Grade 3), Human body organisation (Grade 5), Tissues and organs introduction (Grade 6)
organ system
ScienceFrom Grade 5
a group of organs that work together
Learn it in: Human body organisation (Grade 5), Tissues and organs introduction (Grade 6), Life science review (Grade 6)
organelle
ScienceFrom Grade 6
a small part inside a cell with its own job
Learn it in: Basic cell structures (Grade 6), Life science review (Grade 6)
organism
ScienceFrom Grade 6
a living thing
Learn it in: Cells as basic units of life (Grade 6), Organisation of living systems (Grade 6)
orrery
ScienceFrom Grade 5
a mechanical model of planet motions
Learn it in: Solar System models (Grade 5)
osteoporosis
ScienceFrom Grade 4
a condition where bones become weak
Learn it in: Bone health (Grade 4)
ovary
ScienceFrom Grade 2
the part of the flower that grows into the fruit
Learn it in: Fruits and seeds (Grade 2), Seed formation (Grade 3)
overload
ScienceFrom Grade 4
too many appliances on one socket
Learn it in: Electrical safety (Grade 4)
oxygen
ScienceFrom Grade 2
the gas in air that living things need
Learn it in: What is air? (Grade 2), The lungs (Grade 3)
ozone layer
ScienceFrom Grade 5
a layer that absorbs harmful ultraviolet
Learn it in: Atmosphere (Grade 5)