Polymer clays or plasticine clays are made of synthetic plastics and require âcuringâ or low heat to harden. They stay moldable for a very long time if stored properly in a plastic or metal box (no paper or fabric that would absorb the moisture). Polymer clays are usually very smooth and have a silky feeling.
On average, 4th graders are 9-10 years old because that is the normal age for the grade. But kids could potentially be anywhere from about 8 to 11 years old, since some kids hâ¦ave to repeat a year in school and get behind, and then some kids are a year ahead or have late birthdays before the cut-off date.
Â· just now. Report Abuse. These are the ages when students typically begin each grade: Kindergarten- 5 years old 1st-6 2nd-7 3rd-8 4th-9 5th-10 6th-11 7th-12 8th-13 9th-14 10th-15 11th-16 12th-17 Most leave the grade a year older, unless they have a Summer birthday. They may then be young or old for their grade level.