Objective
By the end of this lesson, you will be able to apply arithmetic skills to solve problems related to rust.
Materials and Prep
- Pencil
- Blank paper
- Ruler
- Calculator (optional)
Prior knowledge of basic arithmetic operations (addition, subtraction, multiplication, and division) is required.
Activities
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Activity 1: Rusty Measurements
Measure the length and width of an object affected by rust using a ruler. Write down the measurements.
Next, calculate the area of the rusty portion by multiplying the length and width. If necessary, use a calculator.
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Activity 2: Rusty Reduction
Imagine you have a piece of metal that is 60% rusted. Calculate the remaining non-rusted portion of the metal.
First, find 60% of the total area by multiplying the total area by 0.6. Then, subtract this value from the total area to find the remaining non-rusted portion.
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Activity 3: Rusty Repair
You have a rusty metal plate that needs repair. The repair process involves removing the rusted portion and replacing it with a new piece of metal.
Measure the length and width of the rusty portion. Calculate its area. Then, find the area of the new metal piece that needs to be cut to replace the rusty portion.
Finally, subtract the area of the rusty portion from the area of the new metal piece to determine how much material needs to be cut.
Fourth Grade Talking Points
- "Rust is a reddish-brown coating that forms on iron or steel when exposed to air and moisture over time."
- "Measuring the length and width of a rusty object can help us determine its size."
- "To find the area of a rusty portion, we multiply its length by its width."
- "When a metal is 60% rusted, it means 60% of its original area is affected by rust."
- "To calculate the remaining non-rusted portion, we subtract the rusted area from the total area."
- "Repairing rust involves removing the rusty portion and replacing it with new metal."
- "To determine how much new metal we need, we find the area of the rusty portion and subtract it from the area of the new metal piece."