As they prepare for their annual back-to-school shopping trip, parents this year will make children scour their closets before agreeing to buy any new jeans, pencils or backpacks. According to NRF’s 2011 Back-to-School survey conducted by BIGresearch, families with children in grades K-12 will spend an average of $603.63 on apparel, school supplies and electronics, within a few dollars of last year’s $606.40 average. Total spending on grades K-12 is expected to reach $22.8 billion.