Fossil formation and geological dating are the focus of this Grade 10 Science worksheet, which explores how evidence preserved in rocks helps scientists reconstruct the history of life on Earth. Students examine how organisms become fossils, what different types of preservation reveal, and how scientists use rock layers and radiometric dating to establish when past organisms lived.

From buried remains to evidence of Earth's past

The reading passage follows fossil formation from burial in sediment through processes such as mineralization, compression, and the preservation of impressions. It explains why rapid burial can improve preservation and why fossilization does not happen to every organism. Students also consider why the fossil record is incomplete and how preservation conditions affect the evidence available to scientists.

The geological dating section introduces stratigraphic succession, the principle that lower layers in an undisturbed sequence of sedimentary rock generally formed before the layers above them. Students distinguish this method of relative dating from radiometric dating, which estimates numerical ages by measuring radioactive isotope decay in suitable minerals. They also examine how dated igneous layers above or below fossil-bearing sedimentary rock can help constrain the age of the sediments.

Evolutionary evidence connects these geological ideas to biological change. Students explore how transitional fossils preserve combinations of features associated with ancestral and later groups, how fossils from successive layers can reveal patterns of extinction, and how fossil distributions and geological settings provide clues about ancient climates and habitats. The passage makes clear that transitional fossils help investigate evolutionary relationships without necessarily identifying a direct ancestor.

Skills and activities

Students apply the vocabulary and concepts through multiple-choice questions, true-or-false statements, concise written responses, matching definitions, a cloze passage, and an extended response. The questions ask them to explain mineralization, interpret the order of rock layers, distinguish relative from absolute dating, and reason about the evidence provided by fossils from different geological periods. The final written task brings these ideas together by asking students to explain how preservation, rock relationships, radiometric dates, transitional fossils, and extinction contribute to our understanding of Earth's history.

What the resource includes

• Student worksheet: Reading passage and activities on fossil preservation, sedimentary rock layers, geological dating, transitional fossils, and extinction.
• Separate answer key PDF: Answers for checking responses and supporting review.
• Student Notes & Lesson Summary: A companion supplement for recording and revisiting key ideas and terminology.
• Separate Teacher Guide: Learning objectives, teaching tips, discussion questions, and common mistakes.

Using the worksheet in class

Use this fossil science worksheet when introducing the fossil record, during a unit on evolution and Earth's geological history, or as a review after teaching relative and radiometric dating. The written explanations provide opportunities to check whether students can distinguish the methods accurately, while the extended response gives them a chance to connect geological evidence with patterns of biological change. The separate answer key and teacher guide provide practical support for reviewing student work and preparing class discussion.

The resource is supplied under the TEKS framework and lists TEKS §112.34(b)(10)(C) and TEKS §112.34(b)(10)(A).