• “Díganle a su compañero 2 maneras diferentes en las que podemos formar 10” // “Tell your partner 2 different ways that we can make 10.”

The purpose of this activity is for students to learn Stage 2 of the What’s Behind My Back? center. Students snap a tower of 10 cubes into two parts and hide one part behind their back. Then their partner determines how many connecting cubes are hidden. Students may use connecting cubes, 10-frames and counters, fingers, or drawings to figure out how many connecting cubes are hidden. As they choose a strategy, they use appropriate tools strategically (MP5). Monitor for students who:

• Create another tower of 10 connecting cubes, snap it into two pieces to show the cubes that are showing, and then count the rest of the cubes to determine how many cubes are hidden.
• Hold up the same number of fingers as the number of connecting cubes that are showing and count the number of fingers that are down to determine how many connecting cubes are hidden.
• Place counters on a 10-frame to represent the connecting cubes that are showing and count the empty squares to determine how many connecting cubes are hidden.

The purpose of this activity is for students to determine how many are needed to make 10 when added to a given number. This activity is presented as the same context as the first activity, except students are not shown the visual of the cubes. Because the context is connecting cubes, one way to determine how many cubes are hidden is to create and snap a tower of 10 cubes. Students may also use their fingers or put counters on a 10-frame. As they choose a strategy, they reason abstractly and quantitatively (MP2) and they may choose to use appropriate tools strategically (MP5).

The purpose of this activity is for students to choose from activities that offer practice with counting, adding, composing, and decomposing numbers.

Students choose from any previously introduced stage from these centers:

• What’s Behind My Back?
• Math Fingers
• Shake and Spill
• Counting Collections
• Roll and Add