• Quick retrieval from earlier learning (Send messages with light and sound). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Does this signal use light, sound or both: a smoke alarm beeping? (light / sound / both light and sound) → soundPrompt: Do you see it, hear it, or both?
2. Ships at sea at night watch for a lighthouse. What message does its light send? (It is time for dinner. / Fish are nearby. / The sea is warm today. / Danger: rocks or land are near here.) → Danger: rocks or land are near here.Prompt: Why would a ship need to know where the coast is?
3. What message does this signal send: a school bell at the end of break? (Playtime is over; go back to class. / Stop and wait. / I need help. / The car is about to turn left.) → Playtime is over; go back to class.Prompt: Where would you meet this signal, and what should you do?

• Ask the class to make a wave with a rope or slinky and describe what moves and what doesn't.
• Share the objective: Send and decode messages using patterns. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: A torch (flashlight) flashes short (•) and long (–) pulses. Use the key to decode the message. Key: D = –•• O = ––– G = ––• Message: –•• / ––– / ––•
• Step 1: –•• → D, ––– → O, ––• → G
• Step 2: So the answer is: DOG
• Answer: DOG
• 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 torch (flashlight) flashes short (•) and long (–) pulses. Use the key to decode the message. Key: R = •–• A = •– I = •• N = –• Message: •–• / •– / •• / –• → RAINPrompt: Each group between the slashes is one letter.
2. In Morse code, MOON is sent as –– / ––– / ––– / –•. How many flashes (dots and dashes) is that altogether? → 10Prompt: Count the symbols for each of the 4 letters.

• 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. A torch (flashlight) flashes short (•) and long (–) pulses. Use the key to decode the message. Key: M = –– O = ––– N = –• Message: –– / ––– / ––– / –• → MOONPrompt: Each group between the slashes is one letter.
2. Why are digital messages less likely to be spoiled by noise than older signals? (Each part is only on or off, so small changes are easy to ignore or correct. / Noise cannot travel through air. / They use no energy. / Digital messages are louder.) → Each part is only on or off, so small changes are easy to ignore or correct.Prompt: Is it easier to tell "on" from "off" or to tell small differences in loudness apart?

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-4.