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Science curriculum for K—5th grades.

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Animals Through Time

Fossils, Animal Survival, & Heredity

2nd Grade, 3rd Grade, 4th Grade

NGSS Standards covered: 3-LS4-1 , 3-LS3-1 , 3-LS2-1 , 3-LS4-3 , 3-5-ETS1-2 , 3-LS4-4 , 3-LS4-2 , 3-LS3-2
In this unit, students develop an understanding of how animals and their environments change through time. Fossils provide a window into the animals and habitats of the past. Analyzing the traits of animals provides evidence for how those traits vary, how they are inherited, and how they have changed over time. Students also examine how the environment can affect inherited traits and determine which animals will survive in a particular environment. Less
  1. Lessons
  2. Activity Prep
  3. Assessments

Lesson 1: Habitats, Fossils, & Environments Over Time

Fossil Dig

THIS LESSON WAS REVISED ON JULY 1, 2019. Here is a link to the previous version.
In this lesson, students explore the idea that the rock under our feet sometimes contains fossils, and investigate how these fossils reveal changes in habitat through time. In the activity, Fossil Dig, students use paper to create a model fossil dig. They identify traits of fossils to determine what the habitat looked like when these organisms were alive. Then they use this information to figure out where some Mystery Fossils belong in their fossil dig.

Number of students:
Fossil Dig printout Print 30 copies
Fossil Dig Answer Key teacher-only resource 1 copy
Fossil Dig Questions worksheet 30 copies
Mystery Fossils printout Print 15 copies
Glue Sticks
30 glue sticks
30 pairs
Dot Stickers
We prefer stickers because they are easier to distribute in a classroom. Tape will also work.
90 stickers
Prep Instructions

We suggest students work in pairs. Homeschool students can work on their own.

Prepare Mystery Fossils

Mystery Fossils will print two per page so you may want to cut each page in half before class. Each student needs a ½ sheet for the activity.

Lesson 2: Fossil Evidence & Classification

Guess What These Animals Eat

In this lesson, students will learn how we can infer what the outside of an animal looked like by using clues about their skeleton. In the visual activity, Guess What These Animals Eat, students examine photos of skulls of both familiar animals and dinosaurs to figure out what each animal eats.

Number of students:
What Do These Animals Eat? worksheet 30 copies
What Do These Animals Eat? Answer Key teacher-only resource 1 copy
Prep Instructions

No prep required.

The activity starts after the fourth exploration video, so teachers may want to hand out the worksheets at that time. The answers to the worksheet are displayed in the slides.

Lesson 3: Fossil Evidence, Trace Fossils, & Animal Behavior

Outrunning CeeLo

THIS LESSON WAS REVISED ON AUGUST 21, 2019. Here is a link to the previous version.
In this lesson, students will learn about how fossil dinosaur tracks reveal how quickly a dinosaur was running. In the activity, Outrunning CeeLo, students figure out if they could have won a race with a dinosaur that was just their size. To determine the winner, students will compare the length of their running steps with the dinosaur’s steps.

Number of students:
Dinosaur Footprints (inches) printout
Here is the printout in centimeters.
Print 1 copy
Run for your life! worksheet
Here is the printout in centimeters.
30 copies
Pen or Sharpie
1 pen
15 rulers
Yardstick or Meterstick
1 stick
Masking Tape
Chalk may work better for asphalt or similar surfaces that tape doesn't adhere as well to.
30 feet
Post-Its (3")
Each student needs their own Post-It.
30 Post-Its
Post-Its (3")
You need 1 Post-It for each dinosaur, but we suggest having a few more in case the Post-It gets blown away.
4 Post-Its
This is enough to make 1 measuring string for each of the four dinosaurs. Yarn or ribbon will also work.
26 feet
Prep Instructions

Find and Prepare Your Racetrack

You will need an area where your students can run for eight steps. Ideally the area will be at least 55 feet (about 17 meters) long. That’s about ⅔ the length of a high school basketball court.

Mark the starting line for the race with masking tape. Establish a line to follow or a destination point to keep everyone running in the same direction.

Check Your Materials

If you’re doing the activity on a gymnasium floor, we suggest students use Post-Its for marking their steps. Test to make sure Post-Its will stick to the surface where you are racing. If your students will be running in the playground, chalk might be a better choice for marking their steps.

Plan For the Race

Each student will run eight steps as fast as they can. Their partner will mark where their eighth step lands.

We recommend that no more than four students run at the same time. If too many students run at the same time, it can be confusing for the markers. Students who are not running or marking can cheer on the runners!

Make the Dinosaur Step Measuring Strings

After the students run, they will measure how far their dinosaur would have run in eight steps using a Dinosaur Step measuring string. There are four dinosaurs, each with a different leg length.

Before class, make the Dinosaur Step measuring strings. Find the black circle on the side of each Dinosaur Footprint printout. Fold two layers of clear tape over the spot to reinforce it. Then use your hole punch to punch a hole where marked. This is where you will tie the string.


Use your yardstick to measure string and cut the following lengths:

  • 68 inches (173 cm) for VeeLo (Velociraptor)
  • 68 inches (173 cm) for SanJuan (Sanjuansaurus)
  • 78 inches (198 cm) for DeeNo (Deinonychus)
  • 88 inches (224 cm) for CeeLo (Coelophysis)

Now you’ll connect the footprints with the strings: thread the correct string length through each hole on the matching dinosaur footprints and tie it on with a knot. Make sure that when the string is pulled straight, the footprints are the correct distance apart. (Distance is shown on the footprint.)


Write each dinosaur’s nickname on a Post-It and stick it to the page where marked (the nicknames are VeeLo, SanJuan, DeeNo, and CeeLo).


Lesson 4: Trait Variation, Inheritance, & Artificial Selection

Designer Dogs

In this lesson, students learn how people create new breeds of animals by mating (selecting) individuals with desirable traits. In the visual activity, Designer Dogs, students are shown pairs of adult dogs and three potential puppies. They study the physical traits of the dogs and look for the puppy that shares these traits.

Number of students:
Designer Dogs worksheet 30 copies
Prep Instructions

We suggest that students work in pairs for this activity. Homeschool students can work alone.

Lesson 5: Trait Variation, Natural Selection, & Survival

Lizard Island

In this lesson, students learn about an example of how nature, not human beings, can slowly change the appearance of an animal using the process of selection. In the activity, Lizard Island, students simulate how natural selection affects a group of tree-climbing green lizards when their island is invaded by hungry brown lizards. This simulation only works for groups of 16 or more students. If you have a smaller group, use the Small Group Version of this activity found in Prep Instructions.

Number of students:
Adopt A Lizard worksheet 10 copies
Baby Lizard worksheet 15 copies
How Many Lizards? worksheet 30 copies
Prep Instructions

If you have a smaller group (between 1 to 15 students), you need to use the Small Group Version of this activity. This version has step-by-step activity instructions on the printout. The step-by-step in the lesson can be used for groups of 16+ students.

Don’t Throw Away Extra Adopt A Lizard Cards

There are three types of lizards in the activity simulation -- Not-So-Good Climbers, Good Climbers, and Excellent Climbers. It’s important that the simulation begins with an equal number of these lizard types. So, if the number of students in your classroom isn’t divisible by 3 (e.g. 28 students), then you will have a few extra Adopt A Lizard Cards printed out. Have students who finish quickly fill out these extra Adopt A Lizard cards.

Prep Baby Lizard Cards

Each student needs a half sheet of the Baby Lizard Cards. Cut each Baby Lizard page in half before class.

Lesson 6: Animal Groups & Survival

Field Journal

In this lesson, students discover why dogs’ expressions, like tail wagging, are so useful when living in a pack. In the activity, Field Journal, students watch videos of different animals that live in groups to simulate observing them in their natural habitats. They discuss and record their observations, and construct an explanation of how living in groups helps these animals survive.

Number of students:
Field Journal worksheet 30 copies
Field Journal Answer Key teacher-only resource 1 copy
8 staplers
Prep Instructions

We suggest students work in table groups of four and share a stapler to construct their Field Journals. Homeschool students can work on their own.

The page numbers of the Field Journal will look scrambled on the printout, but when students fold them and make their booklets, the pages will be in order.

Lesson 7: Environmental Change & Engineering

Bug Off!

In this lesson, students investigate mosquito life cycles and habitats and discover the role of mosquitoes in carrying diseases such as malaria. In the activity, Bug Off!, students evaluate the merits of different solutions for getting rid of mosquitoes at various locations in a town. Students design a solution to help the town deal with an abundance of mosquitoes resulting from a very rainy summer.

Number of students:
Bug Off! Backyard worksheet 30 copies
Bug Off! Picnic Area worksheet 30 copies
Bug Off! Playground worksheet 30 copies
Problem Solver’s Sheet worksheet 30 copies
Prep Instructions

We suggest students work in pairs so they can share their ideas with a partner. Homeschool students can work on their own.

We have provided three Bug Off! worksheets, each picturing a different location in town. In a class, we suggest giving students a choice of which site they’d like to work with. You could also choose to have everyone come up with a solution for the same site. If students finish early, you can have them work on other sites so they can think of multiple solutions to the mosquito problem.

Lesson 8: Traits & Environmental Variation


In this lesson, students examine how physical traits can be influenced by the environment. In the activity, Astronaut-in-Training, students analyze how a NASA astronaut’s traits changed during his “year in space.” Then they measure some of their physical traits (arm strength, height, and balance) and predict how their own traits might change after living in space.

Number of students:
Traits in Space worksheet 30 copies
Traits in Space Answer Key teacher-only resource 1 copy
30 rulers
Post-Its (3")
30 post-its
Prep Instructions

We suggest students work in pairs. Homeschool students working alone will need help with some steps.

Each pair of students will need floor space where they can do push-ups and walk 15 heel-to-toe steps in a straight line. They will also need wall space where they can do push-ups against the wall.