• Observations during small-group work, student interaction, and whole-class discussion will serve to assess student progress.
• Regrouping Math worksheet (M-1-2-1_Regrouping Math and KEY.docx) can be used to assess student understanding.

“These are called base-ten blocks.” Have a student count the number of cubes in one of the 10s. Then lead the student to say there are 10 ones/cubes in each of the 10s. Demonstrate on an overhead or document camera how 10 ones is the same as one 10. 

“If I had 6 ones and 3 ones, how many would I have all together?” Ask for ideas from students. “If I had 6 ones and 4 ones, how many would I have all together?” Have students discuss. Let someone share who brings up that you can have 10 ones, or one 10. Then ask, “If I had 6 ones and I added 6 more ones, how many would I have all together?” Have partners discuss, and then call on a few who mentioned different ideas. One example would be that you could trade 6 ones and 4 ones in for a 10; then you would still have 2 extra ones. Write out a number sentence to show the class 6 + 4 = 10, so there is one ten and two ones.

Repeat this process with a larger decade number. “If I had 1 ten and 8 ones, how many cubes would I have?” Ask for the class to answer together. “How many would I have if I added 4 more ones?” Have partners discuss, and then call one a few who mentioned different ideas. One possible answer would be, “I could combine the 8 ones and 2 ones to make another ten; then I’d have two extra ones. So I’d have 22.” 

Repeat this process until most students seem to have a good understanding of regrouping.

Pass out copies of the Regrouping Math worksheet (M-1-2-1_Regrouping Math and KEY.docx).

Allow students to work in pairs to discuss the strategies they use to regroup the ones into tens. Have actual base-ten blocks available for students who need (or would like) them. Watch for those who have trouble when regrouping into 100. 

After students are finished with the sheet, call the class together. Choose a few of the problems that students had more trouble with. Choose one or two pairs to share strategies for each one. 

Extension:

Use the activities and strategies listed below to meet the needs of your students during the year.

• Routine: As a calendar routine, students can build the number for the date using base-ten blocks. You could ask “How many will we have four days from now?”
• Small Group: Students who might need opportunities for additional learning may need Unifix cubes to start with, as they are easily manipulated. Cubes should be in towers of 10 with 5 each of two different colors. That way if students have two towers of 10 and 5 red and 1 blue, they can see they would need 4 more blue to have another 10. If they had 2 towers of 10 and 3 red, then they could see they would need 2 red and 5 blue for a total of 7 cubes to have another 10.
• Expansion: Students who are ready can practice subtracting one-digit numbers from two-digit numbers using the base-ten blocks. Again, you may need to have some tens made up of 10 ones already put together so they can be easily manipulated.