At a mealtime, use the correct chart for that meal, use the top row to find the approximate number of carb grams Ellie will eat, and the row that has the range which her current blood sugar is (from her sensor). Where the two intersect is the dose she needs for that meal. If she’s eating between meals, or dessert, just use the row for a glucose between 80 and 100 with the column for the carbs for that snack, regardless of what her sugar is at the moment.