Add and Subtract Zero

1. Add and Subtract Zero Unit of Study: Add and Subtract Fluently to 10 Global Concept Guide: 2 of 3

2. Content Development “The 0 facts are certainly the simplest set of facts when it comes to automaticity. Adding or subtracting nothing does not change a quantity. However, while these facts are easy for automaticity, thinking about part of a quantity when the part consists of nothing is a bit confusing. And how are we separating or taking away if we remove nothing? Rather than beginning our study of addition and subtraction with these atypical facts, they are better addressed after our students have had some experiences with +1/+2 facts and have developed a firmer understanding of the addition and subtraction process. Once that understanding is developed, 0 facts come easily for our students” (O’Connell, 2011, p. 52).

3. Day 1 Essential Question: When you add 0 what happens to the sum? Why? • Whole group lesson: Acting Out +0 Facts Problem solving scenarios are used to explore adding zero to a quantity. Class creates an anchor chart to record number sentences. • Math stations • Adding 0 to Ten-Frames – students use ten-frame cards to write +0 facts. • Place the ten-frame cards in a pile face down. Students take turns drawing a card and writing a +0 equation in their math notebooks to represent what happens when they add 0 to the number of dots on the card. • Concentration – students use the +0 facts and the sum to find matches. • Students will need to lay out the 2 piles so all cards are face down. The +0 fact cards are larger than the sums. Students take turns selecting a +0 fact card from a facedown cards and try to find the sum from the other set of cards . Play continues until all matches have been made. • Domino Addition – students use a set of double-nine dominoes or the domino cards to strengthen understanding of the commutative property with +0 facts. • Partners separate the dominoes into 2 piles. Keeping only the dominoes with a 0 on one side and then write any addition equations to show the sums in their math notebooks (ex: 5 + 0 = 5 or 0 + 5 = 5). By the end of Day 1, students will be able to add zero fluently and explain that the sum is unchanged when adding 0.

4. Day 2 Essential Question: How will a number change if you subtract 0 from it? • Whole group lesson - Using Part-Part-Whole Mats to Visualize -0 Facts Students model the action of subtracting 0 using a part-part-whole mat. Students analyze problem solving scenarios to subtract 0. • Math stations • Subtracting 0 from Ten-Frames – students use ten-frame cards to write -0 facts. • Place the ten-frame cards in a pile face down. Students take turns drawing a card and writing a -0 equation in their math notebooks to represent what happens when they subtract 0 from the number of dots on the card. • Domino Subtraction – students use a set of double-nine dominoes or the domino cards to write -0 facts. • Partners find dominoes with 0 on one side and then write subtraction equations to show the difference in their math notebooks (ex: 5 - 0 = 5). They can also find dominoes with the same number on each side and write subtraction equations to show the difference (ex: 5 – 5 = 0). • Fact Family Homes – students practice with fact families to reinforce the connection between addition and subtraction. • Partners shuffle a set of 1-10 number cards and place them in a pile face down. They select a card and write that number and 0 on the door of their fact family house. Then they write one of the four fact family equations in each of the windows of the house. By the end of Day 2, students will be able to subtract zero fluently.

5. Monitoring Progress • Individual Conferencing: • As students work to master their adding and subtracting zero facts, taking the time to confer with individual students allows you to assess their progress and focus them on specific goals. As the students in your class are engaged in Math Stations, invite individual students to meet with you to review their most recent Fact Check and graph their results. Examine blank or incorrect math facts. Ask students which facts are difficult for them to remember. Provide tips and reminders to help students master those facts. Praise each student for the facts she does know and encourage each student to continue reviewing the unknown facts. • Gathering Data Through Observation • Frequently move through the room observing partners as they explore adding and subtracting zero facts. Listen to their discussions to gain insight into their understanding and mastery. Jot down observations to help plan interventions, adjustments to lessons, or task modifications. • Building Automaticity • Once students have explored the concept of adding and subtracting zero and observed and discussed patterns, it is time to check their progress.

6. Literature for your Classroom Library • This story provides the opportunity to explore the sums of numbers when 0 is added. As you read the story, pause slightly to have student predict each subsequent animal using the descriptive clues and the picture of partially molded clay. Stop reading after you show the page with 10 mice. Do not read the last two pages of the book until later in the lesson • Discuss the animals that the rabbit made with the clay. Begin a class chart to record the animals and the quantity of each kind of animal • Read the last two pages of the book, in which Gray Rabbit fell asleep and didn’t make any more animals. He added 0 animals to each group! Have students write number sentences to show the total amount of each type of animal Gray Rabbit made in the What if he added 0 more? column. • Allow students time to discuss their findings and their observations about the sum of any number and 0.