What is Life?

Author(s): SEP Academic staff, past and current

Lesson Overview

Grade level(s):

Elementary School (K-5), Middle School (6-8), High School (9-12), Kindergarten, Grade 1, Grade 2, Grade 3, Grade 4, Grade 5, Grade 6, Grade 7, Grade 8, Grade 9


Biology/Life Science


Common Functions of Living Things

Big ideas(s):

All living things share common characteristics. Living things are made up of one or more cells, use energy (which includes nutrition, excretion, respiration), grow and develop, reproduce, and respond to their surrounding (which includes movement and sensation).

Vocabulary words:

Depending on the age of the students words may or may not be relevant:
reproduction, respiration, excretion, metabolism, growth, development, cell, stimuli, respond, behavior

What you need:

  • 1 bag of 2 specimens from the list below for each pair of students. Pairs will have different combinations of items (alive/not alive; alive/confusing; not alive/confusing). It makes for a very interesting discussion if some objects are given to multiple pairs, but paired with different items.

The following are possible specimens to use. Feel free to come up with your own ideas and vary which specimens are grouped together.

Not Alive
Heat Pack, Candle, Compass, Weasel Ball, Peeping Chick, Toy Car, Baking Soda & Vinegar, Drinking Bird

Bacteria/Mold Plate, Worms, Plant, Isopods, Yeast Bottle, Fungus, Worms, Goldfish, Elodea/Aquarium Plant, Potato or Onion with roots

Seeds, Dried Yeast, Moss, Lichen, Pieces of Wood, Corn Cob, Carrot, Pinecone, Cut Flower, Soil

Non-living materials are available at the SEP Daly Ralston Resource Center (K 118, K137, K138)


Pairs work well


Classroom or lab

Time needed:

One class period 40-60 minutes

Author Name(s): 
SEP Academic staff, past and current

Students will investigate different objects and discuss whether they are alive or not alive. Students are challenged to provide evidence for their decision and defend their opinion.

Learning goals/objectives for students: 

Students will be able to list some characteristics that all living things have in common.

This lesson also allows students to practice:

1) Building a community of scientists
2) Thinking critically and being skeptical
3) Constructing an argument and defending a position

Getting ready: 

Gather objects and place two items in a bag as described above. Have enough bags for each pair of students.

Lesson Implementation / Outline



  1. Whole class or pairs (Think-pair-share): Have students give examples of living and non living things and brainstorm the characteristic functions/characteristics of living things. (Students' response might include: Living things eat, breath, move, die, have offspring, grow, change etc.)
  2. Record students' responses on the overhead or blackboard

Explain activity (student directions are attached to this lesson plan) and distribute bag of items to each pair of students.

Investigation in pairs:
1) Examine your specimens.
2) For each of your specimens, discuss the following questions:
a) How is the specimen like a living thing?
b) How is the specimen not like a living thing?
c) Would you say the specimen is alive or not alive? What is your evidence? (focus on what you can directly observe)
3) Choose the specimen about which you have had the most interesting discussion, and be prepared to present your conclusions about whether it is alive or not. Your conclusions should be supported by your observations.

Report Out:
1) Randomly assign reporter for each pair; have each pair report out.
2) Have the reporter hold up the specimen and describe it to the rest of the class and answer the following:
a) Did you and your partner decide that the specimen was alive, not alive, or are you uncertain?
b) What is your evidence for that decision?

Checking for student understanding: 

Encourage students during their discussion with their partner as well during their report-out to question and challenge each other. Depending on the age of your students you might want to model how to ask clarifying and/or skeptical questions ("Why do you think that?", "What made you decide that?", "But what about ______? How does that fit with your decision?" etc.) Questioning each other does not only challenge students to think deeper but also models how scientists are by nature skeptical of one another’s findings and allows students to become accustomed to defending their positions with evidence.

Wrap-up / Closure: 

Brainstorm a list of the common functions of life: what are things that all or almost all living things do? [Write responses from whole group on overhead/blackboard]

Possible Follow Up Questions:

  • Does each living thing need to do all of these things in order to be considered alive?
  • Given this list, how would you now classify a seed? What about a mule? A mule is the offspring of a horse and a donkey and is usually sterile.

These questions, like so many in science, do not have clear answers. A virus is an example of something that scientists continue to debate whether they are alive or not. Viruses cause diseases (such as the common cold) and are made of a protein coat surrounding the genetic material. They cannot reproduce themselves - they have to subvert the machinery of a host cell. Thus, they exhibit some but not all characteristics of living things. Generally, they are considered not alive, but there definitely is not full consensus and there is always the possibility that as we learn more, our ideas may change.

Extensions and Reflections

Task card.doc22 KB
report out.doc20.5 KB
NGSS Topics
High School Life Sciences: 
NGSS Disciplinary Core Ideas
NGSS Performance Expectations
NGSS Performance Expectations: 
NGSS Science and Engineering Practices
NGSS Crosscutting Concepts
NGSS Topics Engineering, Technology and Applications of Science: 

Standards - Grade 2

Life Sciences: 
2. Plants and animals have predictable life cycles. As a basis for understanding this concept:
f. Students know flowers and fruits are associated with reproduction in plants.

Standards - Grade 3

Life Sciences: 
3. Adaptations in physical structure or behavior may improve an organism's chance for survival. As a basis for understanding this concept:
a. Students know plants and animals have structures that serve different functions in growth, survival, and reproduction.

Standards - Grade 5

Investigation and Experimentation: 
6. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:
a. Classify objects (e.g., rocks, plants, leaves) in accordance with appropriate criteria.


Materials Available at the RC

Hey! We just used this lesson in our classroom. Materials at the RC consist of two boxes, one called Non-Living Things and one called Dilemma (or confusing). You have to collect your own Living Things and bring them into class, but we got some large petri dishes from SEP for some little critters we collected.

It's a great lesson---fun to have the kids talk about what they think about living things, and it gets at some misconceptions, too.