Counting On and Counting Back Unit of Study: Addition and Subtraction Strategies to 20 Global Concept Guide: 1 of 5

Content Development  Counting on from a certain number is the same as adding to that number. Counting on from the greater addend is a helpful strategy that can foster mental math skills.  Students should have opportunities to model addition and subtraction strategies with a variety of manipulatives. For some lessons these manipulatives can be selected in advanced by the teacher, while in other lessons students should choose what will work for them.  The strategies covered in the next unit will repeat throughout the year and into the following grades. Create an anchor chart with your students and add as new strategies are covered.

Day 1 Counting on to add  Students will need to identify which number is greater for this strategy to be efficient. Open the unit with comparing two numbers (0-20) to reinforce the concept of greater and less than.  Go Math Lesson 3.1 will not need to be taught explicitly, as it refers to the Commutative Property taught during Unit 3. This idea can be used to reinforce the counting on strategy by allowing students to choose the greater number as a starting point regardless of the order in the problems.  Probe students about the most efficient way to count on. If you are adding 8+2, is it better to start with the 8 or 2? Why?  Students should be relating the model to a number sentence and recording in their journal.

Day 2 Counting back to subtract  Engage students with I Have… Who Has… to evaluate their progress.  Ask probing questions if the same thinking process is used for addition and counting on applies to counting back to subtract.  Pay close attention when students start counting back:  When subtracting 10-3, do they start counting back at 9 or 10?

Enrich/Reteach/Intervention  Enrich  Go Math Extend the Math Chapter 4 TE 155  Reteach  Go Math ELL Language Support Chapter 3 TE 101B  Intervention/Small Group  Strategic Interventions: Skill 8 – Counting On  Strategic Interventions: Skill 9 – Counting Back