Update all PDFs

Saving Money 1

Alignments to Content Standards: 2.NBT.B.5 2.MD.C.8

Task

Materials

  • Popsicle sticks and rubber bands or base-10 blocks
  • Paper and pencil for each student

Actions

The teacher should pose the following question to students:

Louis wants to give \$15 to help kids who need school supplies. He also wants to buy a pair of shoes for \$39. If Louis gets \$1 every day for his allowance, how many days will it take him to save enough money for both? Explain how you know.

IM Commentary

The purpose of this task is for students to relate addition and subtraction problems to money and to situations and goals related to saving money. This task has students adding two 2-digit numbers that require regrouping and the solution shows a more concrete approach than the solution approach shown in 2.OA, NBT Saving Money 2. This problem can be adjusted based on where students are in their understanding of addition involving two digit numbers.

Teachers can make the problem more personal by letting the student choose a toy he/she wants and the toy their sibling or friend may want and researching the costs. If students do this type of research, they will be engaging in MP 4, Model with mathematics. Students can also choose how much money they want to donate and for what cause. If the students in the class don't receive allowance, the child in the task can make money by helping a neighbor (perhaps walking a dog or bringing in the mail).

This task is part of a set collaboratively developed with Money as You Learn, an initiative of the President’s Advisory Council on Financial Capability. Integrating essential financial literacy concepts into the teaching of the Common Core State Standards can strengthen teaching of the Common Core and expose students to knowledge and skills they need to become financially capable young adults. A mapping of essential personal finance concepts and skills against the Common Core State Standards as well as additional tasks and texts will be available at http://www.moneyasyoulearn.org.

Solutions

Solution: Using bundled objects

To find out how much money he needs to save, we will find 15 + 39. First, let's represent 15 with 1 bundle of ten and 5 single sticks and 39 with 3 bundles of ten and 9 single sticks:

1_f244457079d7280576518b3658f290df

If we put the tens together and the ones together, we have 4 bundles of ten, and 5 singles and another 9 singles:

2_313cad1fbad4305e499ce86b889981c6

If we take 5 singles from the 9 and put them with the other 5:

3_7b06322c2992395cc4969b896167333a

we can make another bundle of ten:

4_90cb7f9232c3694fd494c237fab9c22e

(Students might also take 1 from the five and put it with the 9 to make 10.)

Now we have 5 bundles of ten and 4 singles, which represents 54. Since he gets \$1 per day, it will take him 54 days to save for both.

Solution: Using an empty number line

To find out how much money he needs to save, we will find 15 + 39.

We can start at 15, then count up by tens 3 times, then count up by ones 9 times:

5_2fd0a69b758c99bfa76d2d30c18764a8

It is actually more efficient to start with 39 and add 15 to it; some students will recognize this:

8_8830bc26e634669d703ab4bc41ad95e7

Since he gets \$1 per day, it will take him 54 days to save for both.

Heather_Brown says:

almost 4 years

Providing professional development to Illinois teachers, I am concerned with the alignment of this task. Money is first mentioned in 2.MD.8, later than in most past state standards, a shift that is uncomfortable to many teachers. Centering on "focus", teachers need to be willing to let go of former topics in an effort to provide greater conceptual depth. While I understand that this problem is not as much about money as about addition, I think in an effort to reinforce focus, we need to avoid any items that involve money until 2nd grade.

I am also concerned with the level of this task for 1.NBT.4, which limits addition to a two-digit number and a one-digit number or a two-digit number and a multiple of 10, but this does two two-digit numbers that are not multiples of 10. I like how this problem leads to "Saving Money 2", but I think both of these should be part of 2nd grade, just at different levels within 2nd grade, aligning this problem to 2.MD.8 and 2.NBT.5.

Kristin says:

almost 4 years

Thanks, Heather, that is a great solution to this issue. I've moved the alignment and changed the commentary to reflect your suggestions. Let me know if there is anything else I can do to improve this task.