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.
What grade are 9 year olds supposed to be in?   Generally third, but sometimes fourth, depending on when they were born. How old are you supposed to be in fifth grade? Normally you begin 5th grade at age 10 and turn 11 either sometime during the school year or the summer after, depending on when your birthday is.