3-LS4-3: Why Some Living Things Thrive in a Habitat
Also called NGSS 3-LS4-3 · Topic: Interdependent Relationships in Ecosystems: Environmental Impacts on Organisms · Life Science
The Official Wording
Construct an argument with evidence that in a particular habitat some organisms can survive well, some survive less well, and some cannot survive at all.
Clarification statement: Examples of evidence could include needs and characteristics of the organisms and habitats involved. The organisms and their habitat make up a system in which the parts depend on each other.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What 3-LS4-3 Means in Plain English
Third graders argue, using evidence, that a habitat suits some living things very well, others only a little and some not at all. They match what each plant or animal needs, like water, warmth and food, with what the place offers.
Students treat a habitat and its living things as one system whose parts depend on each other, so a change in one part affects the rest. This builds on 2-LS4-1 and leads to 3-LS4-4, where students judge solutions when a habitat changes.
3-LS4-3 I Can Statements
- I can list what a plant or animal needs to live.
- I can tell which living things fit a habitat.
- I can use evidence to argue why something survives or not.
3-LS4-3 Worked Example
A three-week planting test in a model desert made from a tray of sand.
Which plants can survive in a dry, sandy habitat?
Set It Up: A tray of sandy soil in a sunny window, watered only once a week, holding a small cactus, a pothos cutting and a row of grass seed.
- Plant all three on the same day and water the tray once a week.Same tray, same water
- Check each plant every two or three days and note its color and firmness.Observation log
- After one week, compare the plants.Cactus firm, pothos drooping, a few grass sprouts
- After three weeks, compare again.Cactus fine, grass thin and brown-tipped, pothos wilted
- Sort the plants into three groups: thriving, struggling and not surviving.Cactus / grass / pothos
The cactus did well, the grass barely held on and the pothos wilted, all in the same dry habitat.
Why it works: A cactus stores water in its thick stem, so it fits a dry place, while plants that need steady moisture struggle or die there.
Common Mistakes with 3-LS4-3
Thinking all plants need the same things
“Every plant needs lots of water.”
Try this: Compare a cactus with a fern. Each plant has needs that match its usual home, and those needs differ from plant to plant.
Arguing from one observation
Deciding the grass failed after looking once on day two
Try this: Observe over several weeks and record each check. Plants change slowly, so a claim needs evidence from many days.
Leaving out the reason
“The cactus lived.” with no explanation
Try this: Connect the result to a need and a trait: the cactus stores water, so it can last between weekly waterings.
Where 3-LS4-3 Fits
Practice 3-LS4-3
Quick Check
- A polar bear is moved to a hot desert. Would it survive well?
- Why can a cactus live where it rarely rains?
- What is a habitat?