Bar Models!

This past week, we have been working with bar models to help us think about addition and subtraction problems. Bar models aren't a method of doing addition or subtraction. We will still be using the methods for addition and subtraction - using place value drawings and number-based strategies - that we learned in the fall. Instead, bar models are a great way to think about how story problems work using the beginnings of algebraic thinking.

These pictures show the product of a game we will play to introduce the concept of bar models. Students pull two cards out of a deck, then use two colors of cubes to show the two quantities. Then, they draw a bar model to show the additive process, with an addition and a subtraction sentence that match. The game is also a thinly-veiled excuse to practice basic math facts, and to explore the reciprocal nature of addition and subtraction.

Bar models can model addition problems, which we call "part, part, whole" problems, or subtraction problems, "whole, part, part". If you know both parts and you are trying to determine an unknown whole, it is an addition problem. If you know the whole and one of the parts, then it can be solved with subtraction. The model above can show both of these story problems. Can you figure out which is "part, part, whole" and which is "whole, part, part"? (they are a little sneaky, so read carefully!)

Kate went shopping with her robot two days last week. On Monday, she bought 7 cans of oil. She bought some more on Thursday. At the end of the week, she had 23 cans of oil. How much did she buy on Thursday?

Pete picked 7 pumpkins in the school garden. Maya picked 16 more pumpkins than Pete did. How many pumpkins did Maya pick?

You can do the same thing with larger numbers:

Alex ate 437 pizza slices on Monday. He ate 516 cucumber slices on Tuesday. How many slices of food did he eat on those two days?

Since with this story problem we know both parts, and the whole is unknown, we draw a bar model with the whole as the unknown, shown with a question mark, like this:

If it was a "whole, part, part" story problem instead, the question mark would go in the box of the unknown part instead of under the bracket.

When students get older, bar models can be a visual representation of an algebraic equation, with letters representing the unknown parts or wholes. Students will also use bar models for problems that require multiple steps to solve, as well as problems with more than two "parts" that make up the "whole". Bar models are a very useful tool, and a crucial part of the Math in Focus curriculum.

Bi-weekly update, November 20th

Reader's Workshop
We are doing an author study of Eve Bunting. She often writes about serious subjects, and her books invite good discussions. So far, we read Pirate Boy (a not-so-serious one), Going Home, and How Many Days to America?

We did a lot of reading, looked at the ending -ed, worked on our spelling words, and read a poem about sunrise and sunset.

Writer's Workshop
We are finishing up our bee research writing unit by organizing our bee notes into categories, then picking one bee-related topic and writing a paragraph about it.

Math
We are moving slowly through the subtraction chapter so that students can have time to master three-digit subtraction with regrouping.

Science
We made floating lighthouses, and tried to make floating islands. Guess what! We couldn't make an island float!

We will be studying islands, geology, erosion, and rivers in the next two months!

Social Studies
People have come to America for many reasons. We discussed the places we know our family came from, before they came here, and talked about some of the reasons why they came.

We also started our first Children Discovering Justice unit, about Freedom. Students discussed what is freedom, and if we have freedom in the United States. We talked about how we balance freedoms with laws and rules to keep us safe. Freedom is one reason that some people have come to our country.

News and Other Information
We are about half way through our current homework project, studying a family tradition or celebration. This project is due on December 4th.

The school site council has a survey for families to take:
- in English
- in Spanish
If you would like it translated into another language, please talk to Ms. Kaplan.

Lightship

We read a wonderful book by Brian Floca, called Lightship. This is an informational text, but it reads very differently than most informational texts do. It sounds much more like a story.

To write this book, Brian Floca did lots, and lots, and lots of research. He read books about lighthouses and lightships, he visited actual ones, he talked to people who worked on them, he looked at photographs and diagrams of lightships, he investigated marine charts to see where they were, and he took many, many notes on everything he learned. Then, he turned all of his research into a book!

We also read a Gail Gibbons book about lighthouses, as well as another text that shows lighthouses all around America.

Then, we tried to make our own! We had two main goals: make it float, and make it act as a lighthouse. Some of our designs did both, some only floated but fell over, and some sank.

Writing paragraphs

In writer's workshop recently, we have been working on writing paragraphs. A paragraph is a collection of sentences which all relate to one topic. This is one of the last steps to our research writing unit. Next, we will be pairing our paragraph with some other informational text features to make it easy for our readers to learn about the topics we are writing about.

We started our research process with lots of note-taking. Mr. MacLellan read a page from a book, and then students had a very short time to write a note about what they read. We talked about how notes don't have to be your best handwriting. Mr. MacLellan showed some of his own notes and nobody could read them!

Next, students organized their notes into categories. We color-coded the notes, cut them out, and glued them with similar other notes.

Finally, we started writing our paragraphs. Students picked one topic relating to our research on bees. They wrote a title on the top of their page, and started their paragraph with an interesting question to get the reader interested in reading more. We will be finishing these paragraphs later this week.

For our current homework project, students need to take their notes about the family holiday, celebration, or tradition, and write a paragraph from their notes. They should use the same structure we used in class:

Bi-weekly update, November 6th

Reader's Workshop
We worked on comprehension skills these weeks, focusing on two big skills: asking questions and visualizing. We read a number of magazines, asking and answering questions as we went. To practice visualizing, Mr. MacLellan read a book out loud, having students draw the picture in their head for every few pages. After we were done, we looked at the pictures the illustrator chose, and compared what was the same and what was different.

We talked about defining words,  and groups of students wrote a definition for a number of words relating to bees.

We also continued to study spelling words!

Writer's Workshop
We are fully into a research writing unit, reading books about bees, taking notes, and drawing to help support our research. Next week, we will be writing paragraphs with the information we have learned.

Math
We are subtracting! We are working on three-digit subtraction with regrouping in all places. This has been difficult for many students, so we are taking our time and moving slowly through this unit so we have lots of time to practice.

At home, please practice math facts, especially subtraction! Students should know the answer to any one-digit subtraction facts. If you see that your student doesn't, then practice, practice, practice!

Science
Can you make a heavy thing float? We tried to make clay and rocks float, by choosing materials or shapes that were buoyant enough to support a heavy object.

Since we are learning about bees in writer's workshop, we are thinking about pollination in science, too. We went into the school garden and picked marigold flowers for a dissection. Back in the classroom, we drew them, then picked them apart to see what they look like up close on the inside. We found seeds, lots and lots of seeds! We also looked at garlic chive flowers, and drew those in our science notebook as well.

Social Studies
We learned about the world, thinking about countries, continents, and oceans. Understanding the difference between a city, a state, a country, and a continent is difficult!

News and Other Information
The week of November 16th - 20th is conference week. Tuesday, Wednesday, Thursday, and Friday of that week are half days, with dismissal at 12:15.

Homework project due on Friday!

The students in our room have hopefully been working hard on their book report projects at home! Book reports are due on Friday.

We will be doing our presentations over the whole day. Presentations will just be for our classroom, but we will take videos of each one so that families can see how they went.

Please let me know if you have any questions!

If you need another copy of the letter and checklist, click here to download it.

If you need another copy of the draft paper, click here to download it.

Also, you can look back at the homework page on our website.

Sinking and floating

After studying and comparing solids and liquids, we are thinking about sinking and floating. Before doing any experiments, we developed common definitions for the two terms, so that no matter who does the test, we would all get the same result. We decided that an object that touches the bottom but has a part of it sticking up above the water is too big to test.

Next, we tested a lot of objects. For each one, we predicted if we thought it would sink or float, and explained why. Then we tested. We started to collect all of our data on this T chart:

We then talked about why we think the objects that floated or sank did so. We used sentence frames to make sure we explained our thinking with the word because.

We also thought about displacement. All matter takes up space, and two pieces of matter cannot be in the same space at the same time. So, when you put a solid object into water, it displaces some of the water, and pushes it out of the way. To show this, we took a big plastic tub and filled it all the way to the top. Mr. MacLellan didn't even spill too much getting it to the rug.
We put a small object, a paper clip, into the tub. It displaced so little water, we didn't even see any spill over the sides. Then, we put a rock into the tub. A lot of water spilled over the sides! We then measured how much water spilled out. The little rock displaced 6 cups of water!
Then, we put a big rock in the tub! A little tiny bit of it was sticking out of the water, so it was too big to test, but it displaced more than 11 cups of water.

This week, we took materials that sink and tried to make them float. Some groups tried to make a rock float, and others tried to make a ball of clay float. We tried many different strategies, but most groups ended up taking materials that did float and building a raft. Here, we are testing our designs:

Next, we will be building boats!