MS-LS1-4: How Behaviors and Flowers Help Living Things Reproduce
Also called NGSS MS-LS1-4 · Topic: Growth, Development, and Reproduction of Organisms · Life Science
The Official Wording
Use argument based on empirical evidence and scientific reasoning to support an explanation for how characteristic animal behaviors and specialized plant structures affect the probability of successful reproduction of animals and plants respectively.
Clarification statement: Examples of behaviors that affect the probability of animal reproduction could include nest building to protect young from cold, herding of animals to protect young from predators, and vocalization of animals and colorful plumage to attract mates for breeding. Examples of animal behaviors that affect the probability of plant reproduction could include transferring pollen or seeds, and creating conditions for seed germination and growth. Examples of plant structures could include bright flowers attracting butterflies that transfer pollen, flower nectar and odors that attract insects that transfer pollen, and hard shells on nuts that squirrels bury.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What MS-LS1-4 Means in Plain English
Middle schoolers argue from evidence that certain animal behaviors and plant parts make it more likely that young are produced and survive. Think birds building nests, males singing or showing bright feathers, bees carrying pollen, and squirrels burying nuts that later sprout.
The key word is probability: a trait raises the odds, it does not guarantee success. This builds on plant and animal structures in 4-LS1-1 and leads to how genes and environment shape growth (MS-LS1-5) and natural selection (MS-LS4-4).
MS-LS1-4 I Can Statements
- I can explain how a behavior raises an animal's chances of raising young.
- I can explain how a flower's color or scent helps it make seeds.
- I can support my argument with evidence from data.
MS-LS1-4 Worked Example
A nest model test with warm plastic eggs that a class can finish in one period.
Does a nest help eggs stay warm long enough for chicks to survive?
Set It Up: Plastic eggs filled with 40 °C water, a nest of dry grass lined with feathers, a bare tray and two probe thermometers.
- Fill two eggs with water at 40 °C and slip a probe into each.Both start at 40 °C
- Set one egg in the lined nest and one on the bare tray.Same room, same start
- Read both every 5 minutes for 30 minutes.Nest 37 °C, bare 31 °C at 30 min
- Repeat with a nest of grass only, no feathers.Grass only: 34 °C at 30 min
The feather-lined nest kept its egg warmest, the grass nest less, and the bare egg cooled fastest.
Why it works: Nest material traps air and slows heat loss, so nest building makes it more likely that eggs stay warm enough to hatch.
Common Mistakes with MS-LS1-4
Saying a trait guarantees babies
“Birds with nests always raise chicks.”
Try this: Traits change the odds, not the outcome. Say a nest makes survival more likely, and point to data showing the difference.
Thinking plants try to attract bees
“The flower wants the bee to come.”
Try this: Plants do not choose. Plants with bright, sweet flowers got more visits and made more seeds, so those traits were passed on.
Arguing without evidence
“Peacocks have big tails because they look cool.”
Try this: Back the claim with data, such as how often females choose males with larger, brighter tails, and explain why that matters.
Where MS-LS1-4 Fits
Practice MS-LS1-4
Quick Check
- How do bright flowers help a plant reproduce?
- Why do some herd animals keep their young in the middle of the group?
- How does a squirrel burying acorns help oak trees?