Debate, discussions, hot-seating

Recipes:

Fruit Crumble

Giving instructions

What is a crumble?A crumble is usually a sweet, crispy topping made from flour, butter, and sugar, baked over fruit to make a dessert.

Crumble – A baked dessert with a crumbly topping made from flour, butter, and sugar, usually served over fruit.

Rubbing in – A method of mixing where you use your fingertips to blend butter into flour until it looks like breadcrumbs.

Investigations:
Salt water solution over time - evaporation

Brighter Bulbs

Discussions, explanations, presentation

What does it mean when a material dissolves, and how can we get it back again? Some materials, like sugar or salt, dissolve in a liquid to form a solution. The solid appears to disappear but is still mixed into the liquid. To get it back, we can evaporate the liquid, leaving the solid behind. This is a reversible change.

How can we separate mixtures using filtering, sieving or evaporation?We can separate mixtures based on the properties of the materials in them. Sieving separates larger solids from smaller ones, filtering separates solids from liquids, and evaporation removes liquids to leave dissolved solids behind. These methods work because different materials behave differently. They are all useful examples of reversible changes.

What is a reversible change and how is it different from an irreversible change?A reversible change means we can get the material back in its original form, like freezing water and melting it again. An irreversible change makes a new substance that cannot easily be changed back. Burning, baking, or reacting acid with bicarbonate of soda are examples of irreversible changes. These changes cannot be undone.

What happens when new materials are formed during irreversible changes?Irreversible changes often create new materials, such as gases, ashes, or cooked food. For example, burning wood creates smoke and ash, and mixing vinegar with bicarbonate of soda makes bubbles of gas. These new materials are different from the ones we started with. This shows that some changes are permanent.

Why do we use certain materials for different jobs?We choose materials based on their properties, such as hardness, flexibility, conductivity, solubility, and whether they are magnetic. For example, metals conduct electricity, so we use them in wires, while plastic is an insulator, so it’s used for wire coatings. We can test materials through fair and comparative tests. These tests help us make sensible decisions about how materials should be used.

Dissolve – When a solid mixes with a liquid and seems to disappear, forming a solution.

Evaporation – A process where a liquid turns into a gas, often used to separate dissolved solids from liquids.

Reversible change – A change that can be undone, returning the material to its original state, like melting or freezing.

Irreversible change – A change that creates a new material and cannot easily be undone, like burning or cooking.

Properties – The special features of a material, such as how hard, flexible, or magnetic it is, which help us decide how to use it.