One of the most important things you can purchase for your budding artist, is a Portfolio. Fibo recommends the 11x14" Itoya PROfolios because kids can easily slide their artwork into them and view their artwork safely at any time. Also, this prevents the need to spray anything on to the artwork as they will already be protected in the plastic sleeves.
We recommend buying one portfolio per year and choose their best work from that year to keep in that portfolio. Take the paper in the binding out, flip it over, use a sharpie and write their name and year, and then slide the paper back into the binding. This creates a very organized system and teaches your children how to curate which work they are going to keep (whatever fits in the portfolio) and what they are not.