9.4 Small Group · Group 1
Tier 2 Intervention · Concrete-Representational-Abstract (CRA) · Dual-Language Anchors
solution · substitute · Procedural Fluency · Real-World Applications
- Writing the equation is only half the job. Applying it means substituting what you know, solving for what you don't, and checking whether the answer makes sense in the situation. We'll walk through a worked example, try one together, then you'll try a few with hints right there when you need them.
- The number of cars produced depends on the number of hours of operation. Every hour, the plant produces 2.5 cars.
- Let h = hours and c = cars. The equation is c = 2.5h. Check with the table: 8 hours gives 2.5 × 8 = 20 cars per shift.
- The order needs 1,000 cars, so substitute: 2.5h = 1,000.
- Divide both sides by 2.5: h = 1,000 ÷ 2.5 = 400 hours.
- Interpret it: 400 hours running 24 hours a day is about 17 days — about 2.5 weeks. That fits inside 3 weeks only if the plant runs 24 hours a day, 7 days a week.
- solution (solución) — A value of the variable that makes an equation true.
- substitute (sustituir) — To replace a variable with a number so you can compute.
- at least (al menos) — That amount or more — the smallest amount that still works.
- predict (predecir) — To make a reasonable guess about a future amount using information you already have.
- justify (justificar) — To explain WHY an answer or recommendation makes sense, using the mathematics.
- Adding the rate instead of multiplying — writing 2.5 + 8 = 10.5 cars for an 8-hour shift instead of 2.5 × 8 = 20. The rate applies to EVERY hour, so the total is always rate × amount.
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1 DRAG SORT
Sort each statement about c = 2.5h.
- In 4 hours the line produces 10 cars
- h is the independent variable
- The unit rate is 2.5 cars per hour
- In 2 hours the line produces 4 cars
- c is the input of the equation
- In 5 hours the line produces 25 cars
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2 FILL TABLE
The assembly line produces 2.5 cars per hour. Complete the production table.
Hours (h) Substitute c = 2.5h Cars produced (c) 4 8 (one shift) 100 ✏️ Scratchpad / Reasoning
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3 MULTIPLE CHOICE
The assembly line produces 2.5 cars per hour. How many cars does it produce in one 8-hour shift?
- A20 cars
- B10.5 cars
- C16 cars
- D25 cars
per 1 - 1LabelWrite what each column is.
- 2Find per 1Divide to get one.
- 3ScaleMultiply up to what is asked.
- 4CheckDoes the size make sense?
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4 MULTIPLE CHOICE
Let h = hours of operation and c = cars produced. Which equation represents the assembly line?
- Ac = 2.5h
- Bc = 2.5 + h
- Ch = 2.5c
- Dc = h ÷ 2.5
✏️ Workspace & Solution Steps -
5 MULTIPLE CHOICE
Using the table (1 hour, 2.5 cars; 8 hours, 20 cars; 16 hours, 40 cars), how many cars are produced in 24 hours?
- A60 cars
- B26.5 cars
- C40 cars
- D50 cars
✏️ Workspace & Solution Steps -
6 MULTIPLE CHOICE
Last year the student council washed 34 cars and raised $408. How much did they charge per car?
- A$12
- B$374
- C$34
- D$10
per 1 - 1LabelWrite what each column is.
- 2Find per 1Divide to get one.
- 3ScaleMultiply up to what is asked.
- 4CheckDoes the size make sense?
Complete each sentence stem to demonstrate precise mathematical reasoning:
Writing Task: Justify why your mathematical solution is accurate and complete.