MS-LS2-1: How Food, Water and Space Shape Populations
Also called NGSS MS-LS2-1 · Topic: Matter and Energy in Organisms and Ecosystems · Life Science
The Official Wording
Analyze and interpret data to provide evidence for the effects of resource availability on organisms and populations of organisms in an ecosystem.
Clarification statement: Emphasis is on cause and effect relationships between resources and growth of individual organisms and the numbers of organisms in ecosystems during periods of abundant and scarce resources.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What MS-LS2-1 Means in Plain English
Middle schoolers read data to find out how the supply of food, water, light or space affects living things. They look at both levels: how big each organism grows, and how many organisms a population holds when resources are plentiful and when they run short.
The heart of it is cause and effect read from graphs and tables, not memorized facts. It builds on how plants and animals get what they need (5-LS2-1) and leads to the high school idea of carrying capacity (HS-LS2-1).
MS-LS2-1 I Can Statements
- I can read a graph to see how a population changes over time.
- I can explain how scarce food affects how big organisms grow.
- I can use data as evidence that resources limit a population.
MS-LS2-1 Worked Example
A three-week fruit fly test a class can run in clear vials on a shelf.
Does the amount of food in a vial change how many fruit flies it ends up with?
Set It Up: Six clear vials with foam plugs, mashed banana food, a small scale and 5 pairs of fruit flies per vial.
- Put 5 g of mashed banana in three vials and 20 g in the other three.Scarce vs plenty, 3 vials each
- Add 5 pairs of flies to each vial and keep all six on the same shelf.Same start, same warmth
- Count the adults twice a week by chilling each vial briefly so the flies rest.Day 7: about 10 in every vial
- Keep counting until day 21 and graph the mean for each group.Day 21: about 40 vs about 150
- Look at a few adults from each group under a hand lens.Scarce-food flies look smaller
Vials with more food grew much larger fly populations, and their flies were bigger too.
Why it works: When food is scarce, fewer young survive and those that do grow less, so food limits both the size of each fly and the number of flies.
Common Mistakes with MS-LS2-1
Reading one vial as the answer
“Vial 2 had 30 flies, so scarce food means 30.”
Try this: Average the vials in each group and look at the spread, because one vial can be odd for reasons nobody controlled.
Mixing up cause and correlation
Claiming warm weather caused a deer boom without other data
Try this: Check what else changed at the same time. A resource is a cause only if the data rule out the other changes.
Ignoring individual size
Only counting animals, never measuring them
Try this: Resources affect how large each organism grows, not just how many survive, so record size or mass as well as counts.
Where MS-LS2-1 Fits
Practice MS-LS2-1
Quick Check
- A rabbit population drops during a dry summer. Name one resource that likely ran short.
- Why can a population stop growing even when the animals are healthy?
- Fish in a big pond grow larger than the same fish in a small pond. Why?