Some plastics today would be just as bad, which is why we need to be careful when mixing and storing our clay. Not all plastics are created equal Redmond Clay, dry or hydrated, can be stored safely in the right kind of plastic.
This is Ref to learning new language i know people advance differently but what would be the average age range? Elementary in my state (Florida) is Kindergarten through 5th grade or age 5 by a certain date to age 10-11. Middle School is 6th through the 8th or 10-11 years old through age 13-14. Then high school is 9th through the 12th grade 14-15 years old to age 17-18. In my state they integrate all levels of students together in elementary, but test for Gifted by IQ and give other classes to the really smart students.
The average 6-year-old is about 42 inches tall and weighs almost 50 pounds. Your child will double that weight by the time he reaches adolescence, and grow to five feet tall or more!