This activity gives students an opportunity to determine and request the information needed to determine the total savings after various discounts are applied to different items.  

The Info Gap structure requires students to make sense of problems by determining what information is necessary, and then to ask for information they need to solve it. This may take several rounds of discussion if their first requests do not yield the information they need (MP1). It also allows them to refine the language they use and ask increasingly more precise questions until they get the information they need (MP6).

After students have completed their work, share the correct answers, and ask students to discuss the process of solving the problems. Here are some questions for discussion:

• “What information did you and your partner have to figure out?”
• “How did you determine the cost of Elena's tennis racket?” (I multiplied the original cost by 0.85; I multiplied by 0.15 and subtracted it from the original cost.)
• “How did you determine the total cost after tax for Elena's purchases?” (I multiplied the total by 1.085; I multiplied by 0.085 and added it to the original cost.)
• “What different calculations did you have to make for Andre and Elena’s situations?”
• “Was there information given that you did not need to use?”

Highlight any strategies students used for keeping track of the information they received and how they decided what information they still needed.

In this activity, students continue to practice finding percentages from dollar amounts including commission, tip, and markdown. Some of the questions require multiple steps to solve for the percentage needed. In this activity, students critique a statement or response that is intentionally unclear, incorrect, or incomplete and improve it by clarifying meaning, correcting errors, and adding details (MP3).

The purpose of this discussion is for students to to highlight the importance of interpreting results in the context of the situation to make sure that they answer the question that was asked. Invite students to share their different methods for solving the last two questions. Sequence them so that strategies using diagrams come first, and those using equations come second.

Use Critique, Correct, Clarify to give students an opportunity to improve a sample written response to the last question by correcting errors, clarifying meaning, and adding details. 

• Display this first draft:

  “The markdown is 78.6% because .”

  Ask, “What parts of this response are unclear, incorrect, or incomplete?” As students respond, annotate the display with 2–3 ideas to indicate the parts of the writing that could use improvement.

• Give students 2–4 minutes to work with a partner to revise the first draft. 
• Select 1–2 individuals or groups to read their revised draft aloud slowly enough to record for all to see. Scribe as each student shares, then invite the whole class to contribute additional language and edits to make the final draft even more clear and more convincing.

The key takeaway is that represents the percentage that the sale price is of the original price. The question asks for the percentage that the markdown is of the original price, which is , or .