3-LS4-2: How Differences Help Some Animals Survive
Also called NGSS 3-LS4-2 · Topic: Inheritance and Variation of Traits: Life Cycles and Traits · Life Science
The Official Wording
Use evidence to construct an explanation for how the variations in characteristics among individuals of the same species may provide advantages in surviving, finding mates, and reproducing.
Clarification statement: Examples of cause and effect relationships could be plants that have larger thorns than other plants may be less likely to be eaten by predators; and, animals that have better camouflage coloration than other animals may be more likely to survive and therefore more likely to leave offspring.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What 3-LS4-2 Means in Plain English
Third graders use evidence to explain how small differences among animals or plants of one kind can help some of them survive and have young. A moth that blends with tree bark, or a bush with sharper thorns, is less likely to be eaten.
The idea is cause and effect: a helpful difference means more chances to live, find a mate and leave young, so that trait shows up more often. This builds on 3-LS3-1 and leads to natural selection in MS-LS4-4.
3-LS4-2 I Can Statements
- I can describe differences among animals of the same kind.
- I can explain how a difference helps an animal survive.
- I can use data from a model as evidence.
3-LS4-2 Worked Example
A pick-up game on the school lawn with colored toothpicks standing in for insects.
Do insects that match their background get eaten less often?
Set It Up: 100 toothpicks, 25 each of green, brown, red and yellow, spread over a patch of lawn marked with cones.
- Toss the toothpicks across the marked patch without looking where they land.25 of each color
- Students act as birds and pick up as many toothpicks as they can in 30 seconds.One toothpick at a time
- Count the toothpicks found by color.Red 22, yellow 21, brown 12, green 7
- Repeat the round with a fresh toss.Green found least again
Red and yellow toothpicks were found most and green least, so the insects that matched the grass were most likely to survive.
Why it works: Coloring that blends with the background makes prey harder for birds to spot, so those individuals live longer and leave more young.
Common Mistakes with 3-LS4-2
Thinking animals choose their traits
“The moth turned brown so it could hide.”
Try this: Explain that a moth cannot pick its color. The moths that already blend in survive more often and pass that color on.
Saying the best trait always wins
“Every green insect survives.”
Try this: Point to the data: some green toothpicks were still found. A helpful trait raises the chances of surviving but never guarantees it.
Forgetting the link to having young
Stopping at “it hides better” with no mention of babies
Try this: Finish the chain: hiding means living longer, living longer means more chances to mate, and that means more young with the trait.
Where 3-LS4-2 Fits
Practice 3-LS4-2
Quick Check
- A brown moth and a white moth rest on dark bark. Which is more likely to be eaten?
- How can sharp thorns help a plant leave more seeds?
- Why did the green toothpicks last longest on the lawn?