This lesson can be used as a pre-lesson for the Big Spenders lesson plan.
Students will be able to add and subtract 10 from multiples of 10.
Students will be able to critique a flawed response in relation to adding and subtracting multiples of 10 with academic vocabulary using discussion cards and partnerships for support.
Gather the students together in a comfortable area.
Pass out personal whiteboards and markers to each student.
Write 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 on the whiteboard.
Next to the numbers, write the following question and sentence frame:
How many more is 20 than 10? (20 is ________ more than 10.)
Ask a student volunteer to read the question and sentence frame aloud.
Encourage students to turn and talk to an elbow partner to figure out the answer. Instruct each student to record their answer on their personal whiteboard.
Allow a few students to share out their answers. Explain to the students that all of the numbers written on the whiteboard are multiples of 10. Elaborate that this means that 10 combined with 10 equals 20, 10 combined with 10 combined with 10 equals 30, and so on. Write down 10 + 10 = 20, 10 + 10 + 10 = 30, etc., to support student understanding. Clarify that 20 is 10 more than 10.
Project the Hundreds Chart on the whiteboard and circle the multiples of 10 in the far right column on the chart. Explain to the students that a hundreds chart is one of the tools that can be used to add and subtract multiples of 10. Continue by explaining that some students may also use mental math to add and subtract multiples of 10 if they feel very comfortable with multiples of 10. Clarify that mental math is when you figure out the problem in your head, without using other tools.
Get out base-ten blocks and show students ten groups of ten (the long rectangles). Count by 10 up to 100 using the base-ten blocks, and explain that base-ten blocks are another tool that can be used to add and subtract multiples of 10.
Instruct students to put on their "mathematician hats" because they are going to use their knowledge of multiples of 10 to figure out if you solved a problem correctly today!