Particle Size
Particle size is how big or small the grains are in a material like sand or soil.
Sugar and salt sit in two bowls on a counter. Salt grains are small and pack tightly together. Sugar crystals are larger and leave bigger gaps between them. The size of each grain changes how the material fills space.
Explaining particle size by grade level
Think about making a brick from sand. Big grains leave big gaps between them. Small grains pack close together. The size of each grain changes how strong your brick turns out.
Projects that explore particle size
Particle size affects how well a material blocks water. In a flood-table test comparing four fill materials, sand blocked the most water, while fine gravel and coarse gravel let the most water through. The smaller grains of sand held back more water than the larger grains of gravel.
The size of sand grains mixed into clay affects how well a fired brick holds together. You make two batches of five bricks each — one with fine sand, one with coarse sand — dry them, then fire both at 900 degrees Celsius for 24 hours. After firing, you drop each brick from 2 meters and count how many drops it survives. Coarse-sand bricks last an average of 2.6 drops. Fine-sand bricks survive only 1.6. When the grains are larger, they produce a more durable brick.