Sample from the K-2 Book
Video 4.5
Tangerines with a 100 Board
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Problem:
There are some tangerines in the crate. After 25 were sold, 53 tangerines were left in the crate. How many tangerines were in the crate to start?
Teacher:
This student used our new 100 boards to show the story. The student colored the number of tangerines left at the end in one color, and then the number sold in another color. He understands that putting those together makes the total number of tangerines we had at the start. It’s interesting that he represented the situation using a subtraction equation but described addition.
Sample from the 3-5 Book
Video 6.4
Sharing Dog Food with Color Tiles
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Problem:
On Saturday there were 4 dogs at the shelter. Jian took a donation of 7 pounds of food. If the dogs got the same amount of the food, how much did each dog get?
Teacher:
This is pretty clever. When she chose the square tiles, I was worried about how she could represent the quarters of a pound that I knew were in the answer. Changing one square tile from a unit whole (1 pound) to a referent whole ( 1/4 pound) is a good solution for students who know what they are doing. I will have to circle back to make sure that she can use this representation to come up with an answer. Or I could pair her with someone who has used a different representation but similar strategy …
Problem:
The school council is picking drink cups for the school dance. The plastic disposable cups cost $6.00 for a package of 75. The paper cups cost $3.50 for a package of 50. If they want to rent glasses instead, they would pay 6.5¢ a cup.
Which cups should they choose? You may make your decision based on other factors, but you should also include the price of the cups in your response.
Teacher:
Evelyn’s response is more complete than I might have hoped for. Her graph is done with a discrete set of points—you can’t rent or buy a partial cup. There are three graphed lines, one for each cup option. I was struck by her choice to unitize to 100 cups, despite the fact that none of the cups was sold in packages of 100. It certainly made a clearer answer, both in terms of comparing money and seeing the different prices on the graph. I wondered about the use of the word “price” in the tables. In this case, is “price” the right word or is “cost”?