Curriculum › Math ›Grade 1

Grade 1 Math · Level 2, Add & Subtract to 20

Make 10 to Add Within 20

How the lesson starts: Make 10 to Add Within 20

1. The Duck Bus

   Hi friend! Quack! This is the Duck Bus. Driver Dot drives it. The bus has 10 seats. 9 ducks are on. 4 more are waiting. How many ducks? Let's find out!

2. Fill the bus first

   9 ducks are on. 1 seat is empty. 1 waiting duck hops on. 9 + 1 = 10. Full bus! 3 ducks are still waiting. 10 + 3 = 13.

3. Fill the box

   8 + 5 = 8 + 2 + □. 8 needs 2 to fill the bus. The 5 gives away 2. How many are left? 5 − 2 = 3. The box is 3! Watch out! The box is not 5.