☰ Contents · Natural science

Liquids, diffusion and solids

Lessons 8–10 · 3 lessons · K. T. Suyarov, Z. B. Sangirova, M. T. Umaraliyeva, S. G‘. Xasanova, M. K. Yuldasheva, D. T. Hasanova. Natural Science, Grade 6 (new edition). Republican Education Centre, 2022
10

Solids

Textbook, pp. 25–26
GoalExplain the properties of solids and their importance in daily life and construction.
New words
solid · qattiq jismvibration (to-and-fro motion in place) · tebranma harakatbrick · g‘ishtpottery, ceramic · sopol
Explanation

Solids have a definite shape and volume. Their particles are packed closer together than in other states and only vibrate in place, so they do not leave the object. A desk, a pencil and a pen are solids. Some solids change shape under an outside force: plasticine, dough, clay. Items such as a cauldron, a kettle or a bowl keep their shape and volume even when heated. Houses, bridges and roads are built from solid materials such as brick, cement, sand, wood, iron and marble. Pottery is made of soft clay, baked in a special kiln and cooled slowly. The walls of the Registan madrasas in Samarkand are also built of hard, fired brick.

Worked examples
Plasticine is also a solid but changes shape under finger pressure and stays in the new shape. A desk keeps its shape under the same force.
Sorting: solid – salt, soap, glass, cheese, paraffin; liquid – juice, shampoo, perfume, honey.
Class activity

Mini-project: with plasticine balls and thin wooden sticks (or toothpicks) build models of the three states: solid – particles in a tight lattice, liquid – close but disordered, gas – far apart. Show them to the class. Safety: handle sharp sticks carefully and keep them away from eyes.

Practice
1
How do the particles of a solid move?
2
Name four solid materials used in construction.
3
How is a pottery vessel made?
4
Plasticine is a solid, so why does it change shape easily? Compare with a desk.