Fossils and Evidence of Past Life — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. Which Grade 3 item is the best fossil evidence of a past sea?
A) A river pebble
B) A shark tooth in desert rock
C) A living cactus
D) A modern seashell on a beach
Grade 3 science reads a shark tooth in desert rock as evidence of a former sea.
2. Which of these is NOT a fossil in Grade 3 science?
A) A bone from a cow alive today
B) A fossilized fern leaf
C) A dinosaur footprint in rock
D) A mammoth tooth in ice
A bone from a living cow is not preserved from the past, so Grade 3 science says it is not a fossil.
3. How do paleontologists decide what an extinct animal looked like in Grade 3 science?
A) They guess without using clues
B) They compare fossils to modern animals
C) They read storybooks only
D) They only study rocks
Grade 3 science uses fossil shapes and modern comparisons to reconstruct extinct animals.
4. Which choice lists only trace fossils for Grade 3?
A) Bones, teeth, and shells
B) Footprints, burrows, and coprolite
C) Leaves, twigs, and flowers
D) Sand, mud, and pebbles
Footprints, burrows, and coprolite are all evidence of activity, so Grade 3 science calls them trace fossils.
Part B: Fill in the Blank
Write the correct answer on each line.
1. A bone from a cow that is alive today is not a fossil because it is not old enough.
Grade 3 science says new bones from living animals are not fossils.
2. The empty shape a shell leaves in rock is a mold fossil.
Grade 3 science calls the hollow shape in rock a mold fossil.
3. When minerals fill that empty shape, they form a cast fossil.
Grade 3 science names the filled copy of a mold a cast fossil.
4. An organism with no living members today is called extinct.
Grade 3 science defines extinct as a species with no living members.
5. Fossils are strong evidence about life on Earth in the past.
Grade 3 science treats fossils as evidence about Earth's past life.