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.
Table 135. Average mathematics scale score of 4th-grade public school students and percentages attaining mathematics achievement levels and having 5 or more hours of mathematics instruction per week, by state or jurisdiction: Selected years, 1992 through 2009. 1  State or jurisdiction.