SWBAT solve a problem in which the total and one part are known; SWBAT record combinations of two numbers that make a certain total.

Today everyone becomes a magician as students are able to use a known starting number and one chunk (addend) of that known number, to determine the amount that is being hidden.

5 minutes

Follow the quick flash routine that was established in this previous lesson. Show the students the 3, 4, & 5 dot cards. Then repeat routine with 4, 5, & 6 dot cards. These can also be found in the resource section.

15 minutes

I gather the students in a circle as I introduce this game. I start by showing the students a tower of 5 connecting cubes. I tell them that I am going to break the tower into two pats and I am going to hide one of the parts behind my back. *Break the cubes so that it is broken into two and three. Then show them the tower of three cubes. Then instruct them to think silently about how many cubes are behind my back. I tell them to put their thumb on their chin when they think they know. By doing this you are giving every kid a chance to answer. When you feel the group is ready (might not be all of the kids) ask for volunteers to share not only the answer but also had he/she figured it out. After you have taken a few explanations, then show the students the *How Many In My Hand?* recording sheet (see resources). Demonstrate how to fill out the sheet. Continue to play until the students understand how to not only play but also record their combinations.

*Students should use the number 10.

*Make sure that they start with all of the cubes in one hand to start each round.

I have added the equation column to allow for connection to the combinations and to provide an opportunity to practice standard notation. The use of this notation is an example of **CCSS.Math.Practice.MP4.**

30 minutes

Students play How Many In MY Hand? Although the students are playing together, each person should fill out their own recording sheet (see section resources in previous section). The game is over when the sheets are full. I have included a few examples of students playing the game.

The first video is an example of a student playing but miscounting. She checks her work and fixes her mistake. This is a good piece to show the students why they should check their work.

The second video is of two students playing and you're abel to see what a complete round of the game should look like.

15 minutes

I gather the students back on the carpet to discuss their strategies for solving How Many In My Hand problems. I start by giving each student seven cubes. Establish that each child has seven cubes in all. Show them that you have seven as well. Ask the students to shut their eyes as you hide some of your cubes behind your back (4 hidden and three showing). Then have them open their eyes and look at the cubes you have in front of you. Ask them to figure out how many are behind your back (in your other hand). Remind them that they have seven cubes that they can use to help them solve the problem.

When most of the students are ready, ask for a few volunteers to tell how many they think are behind my back. Some kids will break the tower the same way and count the ones behind their back. Some will count on from the number of the cubes that you have kept visible. Some will just know the fact. The students are constructing viable arguments for their thinking (**CCSS.Math.Practice.MP3**). Model each example with cubes for all to see.

IF there is time continue with a few other combinations.

5 minutes

Students can either work on ten sticks (see resource video) or numeral writing. You should decide who still needs to work on numeral writing based on the work you are seeing.

The video of a girl playing ten sticks is an example of a student using subtraction to figure out an unknown addend of 10 (CCSS.Math.Content.1.OA.B.4).