Elementary Science

Science Focus LessonWeek 4

Polk County Public SchoolsLinda Vendur, Senior Coordinator

Week 4 – SC.A.1.2.3Benchmark: The student knows that the

weight of an object always equals the sum of its parts.

Essential Question:How does the weight of an object

compare to the total weight of the parts that make up the object?

Vocabulary:weightmass

Weight and MassWeight is a measure of how hard

gravity pulls on an object. We measure weight by using a scale.

Mass is the amount of matter in an object. We measure mass witha balance.

You have two identical bags of potato chips.

When bagging the groceries, one bag of chips gets smashed by a can of juice.

If you weigh the bags

what will you find?

The bag of broken chips …. • will weigh more than the bag of whole chips.• will weigh less than the bag of whole chips.• will weigh the same as the bag of whole chips.

When an object is broken into pieces, the sum of the weight of the pieces will be the same as the weight of the whole object.

So, even though the chips are broken in one bag, the bags of chips will weigh the same.

Emily needs to know how much her box of books weighs, but it is too heavy for her scale. How can she weigh her box of books?A. weigh the books without the box

B. weigh one book and add the weight of the box

C. weigh each book and the box and add the weights together

D. take books out of the box until she can weigh it on her scale

You can find the weight of any object if you have the weights of the object’s individual parts. The sum of the weight of the individual parts is equal to the weight of the object.

So, if Emily finds the weight of each book and the box and adds their weights together, she will know the weight of her box of books.

SummarizingIn your Science notebookwrite down what you learned today.

Practice What You Learned…Kim has a hamster that has a mass of 20 grams. She puts it in a cage that has a mass of 200 grams.

What is the mass of the cage with the hamster in it?

Mass of Mass of Mass of

the hamster the cage hamster in cage

20 grams + 200 grams = 220 grams

The sum of the mass of theindividual parts is equal to the mass of the object.

Practice What You Learned… Jane and Glen are collecting canned food for a food drive at school. They collect cans from each class every day for a week. How can they find out the weight of the cans they collected from Miss Smith’s class last week?

Check Your ThinkingHow can Jan and Glen find out the weight of the cans they collected from Miss Smith’s class last week?

They will need to add together the weight of the cans they collected from Miss Smith’s class each day.

SummarizingAnswer the questionin your Science notebook.

Think of a time when you might need to finethe weight of somethingby adding the weight of the parts together.

Independent Practice1. Greg’s teacher told him to weigh

his container at the end of his experiment, but Greg broke the container. How could he find out the weight of his container?A. Weigh the largest pieceB. Weigh one piece and multiply it by fiveC. Weigh something else that looks about the same sizeD. Weigh all the pieces together

2. A factory makes toy dinosaurs by melting blocks of plastic and molding the plastic into the shape of a dinosaur. Each completed dinosaur has a mass of 12 grams. If a single block of plastic has a mass of 90 grams, how many COMPLETE dinosaurs can be made from one block?

A. 7 dinosaurs B. 8 dinosaurs

C. 9 dinosaurs D. 10 dinosaurs

3. Mrs. Simmons' art class is making stars out of thin sticks and small balls of clay, as shown in the picture. What is the mass of each star?

A. 7 grams B. 12 grams C. 25 grams D. 35 grams

Stick 2 grams Clay ball 5 grams

4. Michael put two pieces of wood in one pan of a balance. One piece of wood had a mass of 35 grams. The mass of the other piece was 21 grams. How much mass must Michael put in the other pan to make the two pans balance equally?

A. 35 grams B. 56 gramsC. 45 gramsD. 21 grams

5. Steven is doing a lab to compare 4 types of candy bars. Steven uses a triple beam balance to find the masses of the first 3 candy bars, but the fourth candy bar breaks into 3 pieces before he finds its mass. Can Steven accurately find the mass of the fourth candy bar?

A. Yes, he can find the mass of the biggest piece and multiply it by 3.B. Yes, he can put all 3 pieces on the balance pan and find the total mass.C. No, the pieces will have a different mass from the whole candy bar.D. No, the candy bar lost mass when it broke into pieces.

Check Your Work1. D. Weigh all the pieces together2. A. 7 dinosaurs 3. D. 35 grams 4. B. 56 grams5. B. Yes, he can put all

3 pieces on the balance pan and find the total mass.

SummarizeIn your Science Notebook answer the Essential Question for this Focus Lesson.

Essential Question: How does the weight of an object compare to

the total weight of the parts that make up the object?

Give an example.