Materials and their properties (grade 2) · lesson

Describing materials

💡 We can sort materials by how they look and feel, like hard, soft, or bendy.

A brick is hard. A sponge is soft. A sock is bendy.

Some things float and some sink. Being big or heavy does not decide it.

A big wood log floats. A small metal key sinks. What a thing is made of matters.

🧠 How to think about it

Before you guess sink or float, ask: what is it made of? Wood floats. Metal keys sink.

🏡 Try it at home

Fill a sink with water. Guess first, then test: a spoon, a crayon, an apple, a key. Which float?

💡 Different jobs need materials with different properties.

To soak up a spill, use something absorbent, like a sponge.

To carry heavy books, use something strong, like thick cloth.

We can test materials and use the results to choose.

🧠 How to think about it

What does the job need? A spill needs soaking. So test which thing soaks up the most water. Pick it.

🏡 Try it at home

Spill a spoon of water on a tray. Try to soak it up with a sock, a paper towel, and a spoon. Which works best?

💡 A thing made of small pieces can be taken apart and built into something new.

A block house can come apart. The same blocks can make a car.

The number of blocks stays the same. Nothing is added or lost.

🧠 How to think about it

I had 10 blocks in my tower. I built a car. I did not add or lose any. So the car has 10 blocks.

🏡 Try it at home

Build a tower with 10 blocks or cups. Count them. Take it apart and build a car. Count again!

💡 Some changes from heating or cooling can be undone, and some cannot.

Ice melts into water. Freeze the water, and it is ice again. That change can be undone.

Melted wax gets hard again when it cools.

A cooked egg can't go back to raw. A baked cookie can't turn back into dough.

🧠 How to think about it

Ask: if I cool it down, does it go back? Ice water freezes again, so yes. A cooked egg stays cooked, so no.

🏡 Try it at home

Fill an ice tray with water and freeze it. The next day, let one cube melt. Then freeze the water again.