• Quick retrieval from earlier learning (Uniform acceleration: v² − u² = 2 a s). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. An object starts at 0 m/s and accelerates uniformly at 1 m/s² over 25 m. What is its final velocity, in m/s? (Give 1 decimal place.) → 7.1 m/sPrompt: Use v² − u² = 2 a s.
2. A car travelling at 15 m/s brakes with a deceleration of 10 m/s². What is its braking distance, in m? (Give 1 decimal place.) → 11.3 mPrompt: Final velocity v = 0.
3. A train speeds up from 5 m/s to 20 m/s over 125 m. What is its acceleration, in m/s²? (Give 2 decimal places.) → 1.5 m/s²Prompt: a = (v² − u²) ÷ (2 s)

• Drop a sheet of paper and a scrunched-up sheet together and ask why one falls faster.
• Share the objective: Horizontal projectiles: time of flight and range. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: A ball is kicked horizontally off a cliff 45 m high. Ignoring air resistance, how long does it take to reach the beach below, in s? (g = 9.8 m/s²; give 2 decimal places)
• Step 1: t = √(2 × 45 ÷ 9.8) = 3.03
• Step 2: So the answer is: 3.03 s
• Answer: 3.03 s
• 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 ball is kicked horizontally off a cliff 20 m high. Ignoring air resistance, how long does it take to reach the beach below, in s? (g = 9.8 m/s²; give 2 decimal places) → 2.02 sPrompt: Vertical motion starts from zero vertical velocity.
2. A stone is thrown horizontally at 15 m/s from a cliff 44.1 m high. How far from the base of the cliff does it land, in m? (g = 9.8 m/s²; ignore air resistance) → 45 mPrompt: Find the time of flight from the vertical motion.

• 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 8 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. A ball rolls horizontally off a table 2 m high. Ignoring air resistance, how long does it take to hit the floor, in s? (g = 9.8 m/s²; give 2 decimal places) → 0.64 sPrompt: Vertical motion starts from zero vertical velocity.
2. One ball is dropped and another is fired horizontally from the same height at the same moment. Which lands first (no air resistance)? (They land at the same time / The dropped ball / The fired ball / It depends on their masses) → They land at the same timePrompt: Horizontal and vertical motions are independent.

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