1.MD.4
Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relation- ship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.
Overview:
By using the Grouping and Grazing Activity online, students will be able to practice forming groups of ten and counting by tens and ones. As students master this skill, they can move on to adding and subtracting two 2-digit numbers by groups of tens and ones.
 |
| Counting by 10's and 1's |
 |
| Adding 10's and 1's |
Classroom Activity:
Open the activity by counting a collection as a class. Ask students for different ways to count the collection. Accept and try all suggestions, and if no one suggests grouping by 10, suggest it as a way to try. Lead students in a discussion of which grouping/counting method was most efficient and easy to count (10). Give students time to count their own collections in pairs and record how they counted their collections. As a follow up activity, give students time to play the grouping and grazing activity to extend their learning and to offer additional practice. This activity is great because it differentiates to students of a variety of levels, providing support for students still struggling with counting by 5's or 10's, and challenging more advanced students by applying what they know about 10's and 1's to add and subtract two-digit numbers.
Resources:
