Name: Date:
Student Exploration: Estimating Population Size
Vocabulary: percent error, population, sample
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. A jar contains 100 marbles total. Some are black. If you pull 4 marbles out and 1
is black, how many out of the 100 marbles would you guess are black? I would guess around 25.
Explain. The reason I would guess 25 is because ¼ is the ratio ofblack marbles to other
marbles being pulled out of 100 and ¼ of 100 is 25.
2. A different jar has 100 black marbles. (The total number of marbles is unknown.) If
you pull 4 marbles out and 1 is black, what is your guess for the total number ofmarbles? 400
Explain. I would say 400, because ¼ of 400 is 100.
Gizmo Warm-up
In the Estimating Population Size Gizmo, you will estimate the total
number of fish in a pond. You will do this by tagging and releasing a
certain number of fish, and then “recapturing” some.
To change the number of fish to tag or catch, drag the slider, or click on the
number in the text field next to a slider, type a new value, andhit Enter.
1. Suppose a scientist tags 100 fish, and releases them. (Set the Tagged fish in pond to 100 to show
this.) Later, a fisherman catches 50 fish from the same pond. (Set Fish to catch to 50 to show this.)
The fisherman’s catch is a sample of all fish in the pond.
A. Click Catch and check. Look at the Results table. How many tagged fish did the
fisherman catch? 19
B. What percent of the fish in his sample were tagged? 38%
2. At the bottom of the Gizmo, select Show total fish in pond. How many fish are in this
, pond? 308 This number is the population of fish in this pond.
Student Exploration: Estimating Population Size
Vocabulary: percent error, population, sample
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. A jar contains 100 marbles total. Some are black. If you pull 4 marbles out and 1
is black, how many out of the 100 marbles would you guess are black? I would guess around 25.
Explain. The reason I would guess 25 is because ¼ is the ratio ofblack marbles to other
marbles being pulled out of 100 and ¼ of 100 is 25.
2. A different jar has 100 black marbles. (The total number of marbles is unknown.) If
you pull 4 marbles out and 1 is black, what is your guess for the total number ofmarbles? 400
Explain. I would say 400, because ¼ of 400 is 100.
Gizmo Warm-up
In the Estimating Population Size Gizmo, you will estimate the total
number of fish in a pond. You will do this by tagging and releasing a
certain number of fish, and then “recapturing” some.
To change the number of fish to tag or catch, drag the slider, or click on the
number in the text field next to a slider, type a new value, andhit Enter.
1. Suppose a scientist tags 100 fish, and releases them. (Set the Tagged fish in pond to 100 to show
this.) Later, a fisherman catches 50 fish from the same pond. (Set Fish to catch to 50 to show this.)
The fisherman’s catch is a sample of all fish in the pond.
A. Click Catch and check. Look at the Results table. How many tagged fish did the
fisherman catch? 19
B. What percent of the fish in his sample were tagged? 38%
2. At the bottom of the Gizmo, select Show total fish in pond. How many fish are in this
, pond? 308 This number is the population of fish in this pond.
