Short answer is YES. Australia has the highest skin cancer rates in the world and ACT schools have a duty of care to protect the students and staff (WH&S) under their care from any foreseeable harm, this includes over-exposure to the sun's UV radiation.
Australian schools play an important part in combating skin cancer. By implementing sensible yet effective policy and practices schools can significantly reduce childhood exposure to potentially harmful solar UV radiation 5 days a week.
ACT primary schools, and especially schools with national SunSmart status, should be actively involved in supporting and reminding students to apply sunscreen each day, ie before lunch time (when UV levels peak) and PE etc.
Whilst many Canberra parents may send their child to school with sunscreen applied, to remain effective sunscreen needs to be reapplied after 2 hours, even more often is washed or wiped of. Come lunch time (when daily UV levels peak), students who have not applied sunscreenbefore going outside will be at an increased risk of sunburn and potential skin damage, further increasing their long term risk of skin cancer later in life.
Melanoma is the most common diagnosed cancer amongst young Australians, and as children get older their sun protection behaviour slow, for example hat wearing decreases as sunscreen becomes the "preffered" choice of sun protection amongst teens. Primary schools should therefore be supporting the use of sunscreen.