Every parent should be aware of the SIECUS guidelines for sex education curriculum. These are the guidelines which are most likely being used in the schools.
Level 1 is for middle childhood ages 5-8 Some of the age appropriate subjects according to SIECUS are:
Both girls and boys have body parts that feel good when touched. (p. 11)
Sexual intercourse occurs when a man and a woman place the penis inside the vagina. (p. 12)
Some men and women are homosexual which means they will be attracted to and fall in love with someone of the same gender. (p. 15)
Everyone, including children, has rights. (p. 28)
It feels good to touch parts of the body. (p. 31)
Touching and rubbing one's own genitals is called masturbation. (p. 32)
Intercourse is a pleasurable activity for most adults. (p. 34)
Remember the above is only a portion of the guidelines. Go to SIECUS' own site to find out why good parents should refuse to allow this in school.