Session 2 - Strategies to Add and Subtract within 20

Igniting Background Knowledge (5-10 minutes)

Activity: What’s My Number?

Directions:

1. The facilitator will show cards in random order. Students will call out the number being represented on the 5-drawing model. Students should be fluent and answer quickly. 
   1. Prompt:  I’ll show you a card with a 5-drawing model.  You tell me the number you see. Try not to count each dot, instead notice the quantity. (Show a model of 5-drawings. Students respond). 
   2. Prompt: You’re right! Ready, Set, Show! 
   3. Show one card at a time, in random number order.  Wait for students to call out the number shown.  
2. For incorrect responses, stop and reinforce how many are seen in each row and one full row is a set of 5. 
3. Alternative option: Students match a card with the numeral. This may be done with partners.

• Post or print the Big Ideas Poster  (Slide 4)

• Option for presenting the lesson:  

  • Present the Addition & Subtraction Presentation Slides Part 1: Addition (slides 5 -32)

  • Use the Addition Sets: Problems in the steps throughout the toolkit and have students complete each one as you guide them through the practice. 

• Both options allow the lesson’s problem set to be printed for students to complete with guidance. 

• Students may complete activities with a partner or small group if more support is needed.

• These problems have students practicing the strategies of counting on, making 20 using 10 frames, decomposing numbers within 10,  and using the relationship of addition and subtraction.

•  If students get stuck understanding, here are some ideas for providing support for your students. These will intentionally lead them through the supported practice of the skill to grasp the learning and guide their thinking: 

  • use hands-on materials to manipulate and put in groups.

  • ensure one-to-one counting correspondence is correct. If the student is having difficulty “seeing” numbers on the ten-frames, break down and put the 5s in two separate rows or use a rekenrek.

  • return to simpler problems with numbers adding within 10 and using one ten-frame.