options: Number Systems and Quantity: students learn to understand the complex number system and reason quantitatively.

Counting & Cardinality: students learn to know number names and the count sequence, count to tell the number of objects, and compare numbers.

Measurement & Data: students learn to work with data and measure attributes such as time, money, length, area, and volume. They may learn to compare measurements to operations and convert between different units of measure.

Number & Operations - Fractions: students learn to understand fractions as numbers and may work with them using addition, subtraction, multiplication, and division.

Geometry: students learn to classify geometric figures by their properties, and understand and compare the relationships between them. Students develop and use formulas to compute lengths, areas, and volumes, and they use transformations to generate new shapes and compare existing ones. Geometry can be studied with and without coordinates.

Modeling: students learn to choose and use appropriate mathematics and statistics to analyze real-world empirical situations, improve decisions, and report on their conclusions and the reasoning behind them.

Number & Operations in Base Ten: students learn to work with the base-ten system and build place value understanding.

Statistics & Probability: students learn to analyze and produce data distributions, and build understanding of univariate and bivariate data. They learn to interpret data, make statistical inferences, justify conclusions, understand rules of probability, and use probability to make decisions.

Operations & Algebra: students learn to solve problems using algebraic thinking and operations such as addition, subtraction, multiplication, and division. They may learn to identify and explain arithmetic patterns, evaluate or manipulate numerical expressions, and reason with equations and inequalities.

Ratios & Proportional Relationships: students learn to recognize, describe, represent, and reason with ratios, rates, proportional relationships, and percent.

Functions: students learn to define, use, and evaluate functions to model relationships between quantities.
problem_activity: Task
Amy and Greg look for a method to estimate the number of leaves on a $35$ foot tree in their yard. Greg notices that the tree blocks almost all of the sunlight beneath its leaves so he thinks of the following way to estimate how many leaves are on the tree:
We can first measure the area of the ground covered by the tree.
Then we measure the area of an average leaf.
We will need to estimate how much of its area an average leaf shades and how many leaves lie over an average point under the tree.
With all of this information we should be able to get a good estimate for the number of leaves on the tree.
Amy and Greg find that the tree covers a region which is roughly a circle $30$ feet in diameter. What is the approximate area covered by the tree?
How can Amy and Greg effectively measure an irregular shape such as a tree leaf?
How can Amy and Greg effectively decide what number to multiply by to account for multiple leaves lying over the same area and leaves shading less than their full surface area?
Suppose $a$ is the approximate area underneath the tree, $b$ the average leaf area, $c$ the proportion of its area an average leaf shades, and $d$ the average number of leaves found over a spot underneath the tree. In terms of the numbers $a$, $b$, $c$, and $d$ what formula will Amy and Greg find for the number of leaves on the tree?


correct_option_index: 4

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