1. Making Sense of Sensible (?!?) Rounding Jojo Uichanco / Lukas van Veen

2. “How much?” “HOW MUCH?” “HOW MUCH?” involves a form of measurement : no sensible rounding necessary. How much did he spend? How much did he spend? How much sleep did you get? How much sleep did you get?

3. “How many?” Answer “HOW MANY?” with a WHOLE number by rounding sensibly. How many students does it take to change a light bulb? How many students does it take to change a light bulb?

4. The framework Sensible rounding always asks: “How many?” Sensible rounding always asks: “How many?” Need in the problem  Round down Need in the problem  Round down Need in the question  Round up Need in the question  Round up

5. Example 1. A taxi can carry up to four passengers. How many taxis do we need to carry 13? 13 ÷ 4 = 3.25 A taxi can carry up to four passengers. How many taxis do we need to carry 13? 13 ÷ 4 = 3.25 Round down or up? Round down or up?

6. 3.25 Can 3 taxis carry 13 students?

7. 3 x 4 = 12 students Need is in the question: round up 4 taxis can carry 13 students

8. Example 2. Let’s make (or bake) a cake Hessa needs four eggs to make a cake. How many cakes can she make with 11 eggs? 11 ÷ 4 = 2.75 Hessa needs four eggs to make a cake. How many cakes can she make with 11 eggs? 11 ÷ 4 = 2.75

9. 2.75 Can Hessa make three cakes? 3 cakes x 4 eggs  12 eggs Need is in the problem: round down With 11 eggs Hessa makes 2 cakes

10. Example 3. I need five meters to make a dishdasha. How many dishdashas can I make with 14 meters? 14 ÷ 5 = 2.8 Two or three? I need five meters to make a dishdasha. How many dishdashas can I make with 14 meters? 14 ÷ 5 = 2.8 Two or three?

11. Need is in the problem: round down I can make 2 dishdashas I can make 2 dishdashas

12. Watch out!!! A pizza is cut into six slices. Khalid has 20 slices. How many pizzas does Khalid have? A pizza is cut into six slices. Khalid has 20 slices. How many pizzas does Khalid have? 3 1/3 3 1/3 A pizza is cut into six slices. Khalid has 20 slices. How many whole pizzas does Khalid have? A pizza is cut into six slices. Khalid has 20 slices. How many whole pizzas does Khalid have? 3

13. Watch out!!! A box holds twelve eggs. A box holds twelve eggs. How many boxes are needed for 25 eggs? Round up: 3 A box holds twelve eggs. How many A box holds twelve eggs. How many full boxes can be made with 25 eggs? full boxes can be made with 25 eggs? Round down: 2