• Quick retrieval from earlier learning (Evidence for evolution and how new species form; Classification levels and scientific (binomial) names). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Approximate % difference between human DNA and other primates: chimpanzee 1.2 %, gorilla 1.6 %, rhesus macaque 7 %. Which primate shares the most recent common ancestor with humans? (gorilla / chimpanzee / rhesus macaque) → chimpanzeePrompt: Fewer DNA differences means less time since the two lines split.
2. Approximate % difference between human DNA and other primates: rhesus macaque 7 %, orangutan 3.1 %, chimpanzee 1.2 %. Which primate shares the most recent common ancestor with humans? (chimpanzee / orangutan / rhesus macaque) → chimpanzeePrompt: Fewer DNA differences means less time since the two lines split.
3. Approximate % difference between human DNA and other primates: chimpanzee 1.2 %, orangutan 3.1 %, rhesus macaque 7 %. Which primate shares the most recent common ancestor with humans? (chimpanzee / orangutan / rhesus macaque) → chimpanzeePrompt: Fewer DNA differences means less time since the two lines split.

• Show a microscope image of cells and ask what students think they are looking at.
• Share the objective: Read cladograms and shared derived traits. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: A cladogram branches in this order: lamprey, shark, frog, lizard, mouse. New traits: jaws appears before the shark branch; four limbs appears before the frog branch; amniotic egg appears before the lizard branch; hair appears before the mouse branch. Does the shark have four limbs?
• Step 1: four limbs appears after the shark branches off, so it lacks it.
• Step 2: So the answer is: no
• Answer: no
• Pause after each step and ask a student to say what comes next.

• Do these together. Students try each step on whiteboards before you reveal it.
• Use the hints as prompts rather than giving the answer.

1. A cladogram branches in this order: lamprey, shark, frog, lizard, mouse. New traits: jaws appears before the shark branch; four limbs appears before the frog branch; amniotic egg appears before the lizard branch; hair appears before the mouse branch. Does the lizard have amniotic egg? (yes / no) → yesPrompt: A trait is shared by every branch that splits off after it appears.
2. A cladogram branches in this order (first branch = most distantly related): lamprey, shark, frog, lizard, mouse. Which of these options is most closely related to the lizard? (lamprey / mouse / frog / shark) → mousePrompt: Organisms that branch off later are more closely related to each other.

• Students work on the student sheet. Circulate and check the first two answers of every student early.
• Students who finish: write a question of their own for a partner, with the answer.

The 6 questions are on the student sheet below, with answers in the key.

• Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.

1. Modern classification groups organisms into three domains. Which list is correct? (Plants, Animals, Fungi / Vertebrates, Invertebrates, Plants / Prokaryotes, Protists, Viruses / Archaea, Bacteria, Eukarya) → Archaea, Bacteria, EukaryaPrompt: This system was proposed by Carl Woese using RNA evidence.
2. A cladogram branches in this order (first branch = most distantly related): lamprey, shark, frog, lizard, mouse. Which of these options is most closely related to the frog? (lizard / lamprey / shark) → lizardPrompt: Organisms that branch off later are more closely related to each other.

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-12.