Many students find that adding and subtracting rational expressions can be complicated because there can be numerous steps used to solve an equation. Given all these steps, it’s easy to make mistakes, but there are ways to avoid common mistakes. For example, a student might use line paper so that her steps are clear, while another student may know a trick for checking her answers midway through a problem.What method or methods do you use to ensure you don’t make small mistakes when adding and subtracting rational expressions?How do you stay organized with your steps when you add or subtract rational expressions?Does your approach seem to work well? Why or why not?

Progress Check Use this activity to assess whether you and your peers can:  Use histograms to compare shape, center, and spread in the distribution of a quantitative variable for two groups of individuals. Context Students researching backpack weights gathered data from 45 elementary school children in the 3rd and 5th grades. The variable is “percent of body weight carried in the school backpack.” So a child who weighs 60 pounds and carries 9 pounds has a variable value of 15% (9 ÷ 60 = 0.15 = 15%). The American Chiropractic Association (ACA) recommends that children carry no more than 10% of their body weight. Prompt When we analyze backpack weight as a percentage of body weight, how do 3rd and 5th graders compare? Are children in this study following the ACA recommendation? Percent of Body Weight Carried% of body weight carried in backpackThird gradersFifth graders  0-5%11  5-10%66  10-15%114  15-20%37  20-25%01  25-30%02  30-35%01Totals2122 Note: Left-hand end-points are included in each bin. So the 2nd bin contains students carrying 5% of their body weight.