Hundreds Chart Unit of Study: Strengthening Critical Area: Understanding Place Value to Add and Subtract Global Concept Guide: 3 of 3

Content Development  Students need to see multiple representations and strategies to add and subtract using place value. They have had many chances to find patterns and count by 1’s and 10’s using a 100/120 chart, and can build on these experiences to add/subtract larger numbers.  Using hundred charts to add/subtract larger numbers can build students’ understanding and set a foundation for addition/subtraction with regrouping.  Make connections to open number lines and adding on a hundreds chart.

Day 1  Day 1 – Students should be using a completed 100/120 chart to model addition and subtraction. Boards can be laminated or placed in plastic sleeves so students can track their thinking.  Have students explain their thinking in terms of tens and ones, and how they moved on the hundreds chart.  Example: I started at 73. I had to add 25 more, so I moved down two tens and counted on 5 ones.

Students should make connections to adding and subtracting on a hundred chart to their previous work with open number lines.

Day 2  Day 2 will build on Day 1 by using a blank 100 chart for students to mentally be able to count to add and subtract.  The use of a blank hundred chart will help students develop an understanding of how to visualize the process.  With some experiences on a blank chart, students can begin to model this process on paper without the grid and verbally.

Enrich/Reteach/Intervention  Reteach/Intervention  Using Hundred Chart To Add 1 more/1 less – Interactive activity Using Hundred Chart To Add 1 more/1 less  Subtracting on a Hundred Chart Subtracting on a Hundred Chart  Colored Hundred Chart – help with visualizing patterns Colored Hundred Chart  Enrich  Hundred Chart Puzzle Hundred Chart Puzzle