Fossils and geological time are central to understanding how life on Earth has changed. This Grade 7 science worksheet explores how fossils reveal evidence of ancient organisms and environments, how scientists estimate the ages of rocks, and how fossil distributions show changes in biodiversity across geological periods.

Students work with the distinction between relative dating and absolute dating. They examine how the positions of undisturbed sedimentary rock layers establish the sequence of past events, while radioactive decay can provide numerical age estimates for suitable rocks. The reading passage also explains why the fossil record is incomplete and why scientific explanations must account for uncertainty and gaps in the available evidence.

What students investigate

The activities connect geological evidence with scientific reasoning rather than treating fossils as isolated facts. Students consider how bones, shells, leaf impressions and footprints provide clues about past life. They compare fossil evidence from different geological periods to investigate biodiversity, including the appearance of new groups and the disappearance of others.

The worksheet also reinforces how scientists build and revise explanations. Students consider why not every organism becomes fossilized, how rocks may be changed or destroyed, and why new fossil discoveries can require earlier ideas to be reconsidered. The reading passage introduces respectful use of local First Peoples' perspectives, emphasizing attribution and learning from sources shared by those communities rather than making assumptions.

Activities and question types

• Multiple-choice questions assess fossil evidence, rock-layer order, dating methods, biodiversity and scientific revision.
• True-or-false statements check understanding of fossil preservation, radioactive decay and limitations in the fossil record.
• Short-answer responses ask students to distinguish dating methods, explain gaps in fossil evidence and describe how fossils reveal biodiversity changes.
• A labelled diagram, categorizing task and short note provide additional ways to work with the topic and communicate scientific ideas.

Included with the worksheet

• A printable student worksheet with a topic-focused reading passage and varied response activities.
• A separate PDF answer key for checking student responses.
• Student Notes lines at the bottom of the worksheet for recording key ideas.
• A Teacher Guide inside the answer key PDF, including Learning Objectives, Teaching Tips, Discussion Questions and Common Mistakes.

Practical classroom use

Use this geological time and fossils resource during a unit on Earth's history, as guided reading followed by independent practice, or as a review of evidence and dating concepts. The reading passage establishes the key ideas before students apply them in questions and written explanations. Short answers provide opportunities to check whether students can explain the difference between relative and absolute dating instead of simply recognizing the terms.

For teachers, the separate answer key and embedded guide provide a practical reference for reviewing responses, prompting discussion and addressing common misunderstandings. The resource is designed around evidence-based explanations: students practise using what fossils and rock layers can show while recognizing that scientific conclusions may change when further evidence becomes available.