• Quick retrieval from earlier learning (One material, many objects; one object, many materials). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Which of these is usually made of wood? (a cricket or baseball bat / a window / a mirror / a drinking glass) → a cricket or baseball batPrompt: Think about how each object feels and what it needs to do.
2. Three of these are usually made of fabric. Which one is NOT? (a sock / a pillowcase / a curtain / a paperclip) → a paperclipPrompt: Name the usual material of each object.
3. A chair can be made of wood, metal or plastic. Which property must ALL chair materials have? (soft like a pillow / strong enough to hold a person / see-through / stretchy) → strong enough to hold a personPrompt: What is a chair's main job?

• Pass round objects made of different materials and ask why each one was chosen.
• Share the objective: Build, take apart and rebuild with the same pieces. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: Ben builds a house from 32 building bricks, then takes it apart and uses every brick to build a bridge. How many bricks are in the new model?
• Step 1: The same pieces are just arranged differently.
• Step 2: So the answer is: 32
• Answer: 32
• 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. Kai builds a tower from 33 building bricks, then takes it apart and uses every brick to build a car. How many bricks are in the new model? → 33Prompt: Were any bricks added or lost?
2. A model castle is made of 12 wooden blocks. Each block has a mass of 10 g. The castle is taken apart and rebuilt as a boat with all the same blocks. What is the mass of the boat? → 120 gPrompt: Does changing the shape change how much material there is?

• 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. An old wooden shed is taken apart. How could the planks be reused? (Turn them into glass. / Melt them into metal. / Nothing can be made from used wood. / Build them into a raised flower bed.) → Build them into a raised flower bed.Prompt: The planks keep their size and strength.
2. A model castle is made of 14 wooden blocks. Each block has a mass of 5 g. The castle is taken apart and rebuilt as a boat with all the same blocks. What is the mass of the boat? → 70 gPrompt: Does changing the shape change how much material there is?

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-2.