11-1-17 Scientific Models - PowerPoint Presentation

Slide1

11-1-17 Scientific ModelsSlide2

Do Now: Copy down the following essential

questions in your notebook

and attempt to answer them.

What is a scientific model?

What are the benefits and limitations of scientific models?Slide3

Homework: Benefits and Limitations of Scientific Models worksheetSlide4

Changing Science Research Project Makeup Assignment

You are eligible to retake if you scored 9.5/12 or less on the presentation.

Basically the same assignment as the presentation, but in the format

of written answers.

Directions:

At home: do your research (find at least 2 sources). Be able to answer the Essential Question.

Let Mr. Santos know the day before when you are going to come in early (8:15am)

Come in to class before school with your 2 sources and answer the questions on the worksheet. (Even if you answer these at home, you will

not

be able to look at these answers and you must be able to answer the questions in your own words!

Be able to answer the Essential Question: What is another example of a scientific idea that has changed over time?

Use the following format: Scientists

used to think ________, but now they know ______ because

___________.

You will need to be able to answer

these questions in your own words!!! Slide5

Scientific Models

SC.7.N.3.2:

Identify the benefits and limitations of the use of scientific models

.

This will be the last topic before the NATURE OF SCIENCE UNIT TEST ON THURSDAY, 11/9/17

Write this down in your agenda!!!Slide6

Lesson Objectives

I can explain how scientists use models.

I can explain the benefits and limitations of scientific models.Slide7

We often want to predict or explain things that are pretty complicated.

For example, this basketball player might want to know how many points he will score in his next game.

That will depend on many factors, including how many minutes he plays, if he stays healthy, and whether the person guarding him is good at defense. These things, and more, will decide how many points he will eventually score. Slide8

Why we need scientific models?

Scientists face the same problem as our basketball player. Their job is to explain and predict complicated processes in nature. These processes often involve many factors.

For

example, astronomers want to know the structure of our universe, which consists of billions of stars, planets, and other objects.

Science

also tries to understand processes like how the climate on Earth is changing, or the relationships between different species in a habitat.

Science

also tries to understand the inner workings of a single species, including their cells and DNA.

All

of these things are so complex that we need to simplify them in order to understand them, or to make useful predictions about them.

This is one of the main tasks of scientists

.Slide9

Models in Science

Scientific Model: a simplified representation of an object, event, or process.

Examples include a 3-dimensional object, diagram, graph, equation, map, or written description

Scientific models simplify an object or process into only its most important parts, which makes it easier to understand.Slide10

Examples

The models of the atom and food web

show relationships between different objects

, like atomic particles or animals. They show how different parts of a whole are positioned or related to one another.Slide11

Examples

Other types of models may

represent an event or process.

Ex: a

diagram of the movement of Earth’s crust by plate tectonics.

Ex:

an equation that represents evolution from one generation to the next by natural selection.Slide12

Practice: Think-Pair-Share

True or false, a model is always a 3-dimensional, physical representation of an object or process? Explain your answer.

Answer: False, a model doesn’t have to be a 3D object. It can be a graph, map, equation, or diagram.Slide13

Practice: Think-Pair-Share (with a different person)

Which of these scientific discoveries are models?

The solar system, water cycle, temperature graph, and population equation are all examples of models. The discoveries about water and cheetahs are observations.Slide14

A more specific example: Mendel’s question about inheritance

To understand how models are created, and how they can be useful, let’s look at a specific example. You may have heard of the scientist and monk

Gregor

Mendel and his model of inheritance. Slide15

Mendel’s question about inheritance

Mendel had a very specific purpose.

He wanted to be able to predict what the offspring of two parents would look like

. Specifically, he wanted to help animal or plant breeders predict what would happen when two specific parents were bred with one another.

The

process of

inheritance

is obviously very complicated.

So what Mendel wanted to do was create a simple model - based on math - that enabled him to understand how inheritance worked.Slide16

Mendel’s Experiment

What Mendel did was cross - or mated - many different pea plants. He then grew the seeds from these crosses and compared the features of the parents with their offspring. Mendel did this with thousands of pea plants and noticed a pattern. Slide17

Mendel’s Experiment

When he started by crossing a purple-flowered pea plant with a white-flowered pea plant, he found that all of the offspring had purple flowers

.

But

when he crossed all of the offspring with purple flowers to each other, one-fourth, or 25%, of them had white flowers, and the rest had purple flowers. The white flower skipped generations!Slide18

Mendel’s Model of Inheritance

To explain these puzzling results, Mendel created a model.

Flower color: two factors – purple and white

Each factor is inherited randomly from each parent Slide19

Mendel’s Model of Inheritance

To explain these puzzling results, Mendel created a model.

Flower color: two factors – purple and white

Each factor is inherited randomly from each parent

One factor dominates the other

Dominant trait = P

Recessive trait = pSlide20

Mendel’s Model: Limitations

Model can only approximate

Factors are passed on by chanceSlide21

Model Limitations: not always exact

Models are never exactly correct; they are simplifications

Chance events can affect results

Best models = best approximation of realitySlide22

Model limitations: not always exact

Scientists can account for this uncertainty by allowing their models to predict a range of values that are most likely.

For

example, we know that electrons orbit around the nucleus in particular paths, but can never know the exact location of an electron in an atom.

Therefore

, atomic models like the one shown here highlight the areas where an electron is most likely to be found.Slide23

Practice: Think-Pair-Share

Choose the correct statement about the predictions of scientific models.

One model of Earth’s climate predicts that global temperatures will rise by 2.5 – 5.0



F. The model gives a range, because there are some uncertainties about future human behavior.

A model that is not exactly correct is useless.

An evolutionary model says that orangutans evolved between 12 and 16 million years ago. Because this model does not give an exact value, it must be wrong.

If I cross two pea plants and get something slightly different than predicted by Mendel, his model should be thrown away because it is incorrect.Slide24

Model Limitations: Simplification

Mendel’s model, and other scientific models, have another limitation. Mendel’s model worked well for predicting inheritance in pea plants. But many organisms’ characteristics are not inherited in the way he proposed for pea plants.

For

example, some characteristics in humans like freckles or dimples are controlled by two factors, just like flower color in pea plants. Slide25

Model Limitations: Simplification

But

human features like height and hair color are controlled by more than two factors. Therefore, we cannot use a Punnett square to understand how these traits are passed from parent to child.Slide26

Model Limitations: Simplification

Many models work in some cases but not others

.

For

example, a model of Earth’s climate would not work on Mars. Or a model of human behavior might not work for birds.

This

is

okay,

as long as we know exactly what we are trying to understand. Models are supposed to be simplified representations. No model can explain everything about the universe, or it would be too complex to use or understand.Slide27

Practice: Think-Pair-Share

Choose all the statements that are correct about this model of a dolphin’s body parts.

This model is useful for comparing positions of the heart, kidney, and liver of the dolphin.

This model should not be used to understand a shark’s anatomy, since sharks don’t have a bony skeleton like dolphins.

This model does not show the dolphin’s muscles, so it is incorrect and should not be used for any purpose.Slide28

Benefits of Scientific Models

1.

They simplify complex processes

.

Inheritance is quite complicated, it involves cell division, genes, and DNA. But Mendel’s model allows us to predict the outcome very accurately.Slide29

Benefits of Scientific Models

2. They lead to new discoveries

Using Mendel’s model of inheriting factors, a scientist named Thomas Hunt Morgan studied fruit flies and discovered that these factors, now called genes, were found on chromosomes. Chromosomes were eventually found to be made of DNA.Slide30

Benefits of Scientific Models

3. They can be improved upon

Ex: discovering a new fossil can improve a model of evolution.

Ex. Dr. Morgan found Mendel’s model of inheritance did

not

work for eye color in flies. But, he was able to build upon Mendel’s model to create a new one to better predict inheritance of fly eye color.Slide31

Practice: Think-Pair-Share

Choose

all

ways in which Mendel’s model was beneficial.

Mendel’s model simplified the complex process of inheritance.

Mendel’s model allows us to accurately predict the inheritance of characteristics ranging from flower color to freckles.

Mendel’s model eventually led to the discovery of genes, chromosomes, and DNA.

Thomas Hunt Morgan improved Mendel’s model so that he could predict in heritance of fruit fly eye color.Slide32

Lesson ReviewSlide33

Lesson Review

Models are limited by:

Accuracy

How they can be applied

Models are beneficial because:

They are simple

They lead to new discoveries

They can be improved upon