Mental Computation: Adding 2-digit Doubles and Near Doubles

In Maths groups we have been working on mental computation strategies for addition. My group has been working on adding 2-digit doubles eg. 20 + 20. Students have picked up the concepts very quickly and have powered through the work I have provided. As a result, I have developed a number of resources to use with this concept in order to ensure that the new learning is consolidated. While mostly related to Year 2 (particularly in terms of the Australian Curriculum and Common Core State Standards in the USA) it could be useful for Year 3 teachers when revisiting mental strategies.

This is my latest resource to be added to Teachers Pay Teachers. At 40 pages, it ended up being quite a bit of work - particularly when I forgot to save a day's work before shutting down the computer! (Yes, I still make stupid mistakes from time to time!) So, if you like the look of it, please recommend it to any of your friends who teach Year 2/Grade 2.

From a technical perspective, this new resource contains some of my unique clipart, borders and fonts. Still amateur, but improving, I think. The borders were actually much easier to insert than I first imagined, and it's nice to see my 'Me' font and 'Cutesy' font on something I have created.

Product Description:
40 pages of resources to support the teaching of two-digit addition using doubles and near doubles. Aligns with Common Core and Australian Curriculum for Grade 2. Concepts move from know facts of doubling 1-digit numbers, through multiples of ten, multiples of five, 2-digit without regrouping, problem solving, related subtraction facts, and near doubles.

Included in this packet are:
Instructions for use
Connections with standards
6 If...Then...Posters
8 Worksheets with Answer Keys
3 Games or Centre Activities
Review Quizzes and Assessment with Answer Keys

Visit my Teachers Pay Teachers store for more information.

Friday Fun - 27/3/09

Fun this week:

Maths
After all the difficulties with teaching subtraction with trading last week, I couldn't simply move on and ignore it. It was eating away at me. I had to conquer it. So this week, rather than moving on to multiplication and division, I spent some more time on subtraction. I found some great videos on subtraction with regrouping and played these for the class.


We then used the rhyme "If there's more on the floor, then go next door" to help us solve a range of two digit subtraction questions. This also helped with explaining the more difficult subtractions from 2000 etc. The rhyme can be applied by the first neighbour saying "I'm sorry, I don't have any numbers to spare. Let's try next door" and so on. I think my students really enjoyed the idea of the numbers being characters and fitting into a story!

My new challenge is to help my students to look at the question first before flying into the written solution. Too many were using the written method to find the answer to 50 - 49 which I know they can do mentally!

We also touched a little on multiplication and division (as I didn't want to overlook it completely) by reviewing some one-digit multiplication and creating the "families" for those facts. For example, 5x7=35; 7x5=35; 35 divided by 7=5; 35 divided by 5=7. Again, my students loved this idea of the numbers being in families. I'll have to remember this as I teach them other concepts - they like to bring the numbers to life!

Spiders in Spider Webs
This relates to our Rowan of Rin unit, but we did it in our homeclasses, so I've decided to include it in Friday Fun. We listened again to the passage in chapter 6 of Rowan of Rin where the characters face thick spiderwebs covered in big, black spiders. We used white oil pastels on black paper to create a web background. We then created our own spiders from shiny black paper and stuck them on the background so that they stood on the page with bent legs. We made the web sparkle in some places using some silver glitter paint. They look really fantastic displayed in our classroom.
Jonno and I were chatting about how great they were and that chatting lead to more ideas and so we decided it would be good to teach the kids how to write a description about spiders and spider webs and then attach their writing under their artwork on the display. We brainstormed some good adjectives and then students created sentences using these words. I suggested that they try some alliteration and rhyme but use no more than three adjectives per sentence. The writing that resulted was really fantastic. One of my students then suggested that we type up these descriptions in our lab lesson rather than handwriting the final copy. Brilliant idea - and a brilliant opportunity to teach some simple word processing tips - changing the page orientation, selecting all text, changing font etc. This lesson was also great for teaching the correct use of commas.

Communication - Assessment Task
As part of our Integrated Inquiry this term, we want our students to learn how to communicate effectively with others through a variety of forms. In groups, students selected a type of communication: phone calls, email, letters, postcards, cards, face-to-face, blogs, SuperClubsPlus webpages. In these groups they needed to consider the purpose for this communication (including advantages and disadvantages), the conventions and tips to effective communication with this form. They then needed to decide on the best way to present this information clearly to their peers - all while cooperating with others in their group.
Students had most of Friday to work on this, but still need a little more time to fine tune their presentations. They have been working very well together and have been learning a lot both about and through communication.

Description
Both literacy classes did some descriptive writing this week using some ideas we obtained through PD last week. I found this picture of a soldier with a kitten. Students began with the sentence "[Name] is a soldier." They then wrote a description of his clothes, his face and the kitten in his arms. After this, students wrote a flashback to tell the story of how the kitten came to be in the soldier's possession. Linking the flashback to the description was pretty tricky for most students and didn't come naturally. This is something for us to work on in future lessons.

Earth Hour
On Friday our school turned off all electrical power between 11am and 12pm in recognition of Earth Hour. We tried to continue with lessons as much as possible. In Year 4 students wrote in their reflective journals and moved to spaces in the room with greater natural light.

Walk-through of Cross Country
Our Cross Country carnival is two weeks away so on Wednesday we walked the course that students will run - just to make sure they know where they will be going. The next day some of the students were complaining about how their muscles were sore from walking the track. Looks like we have some training to do before the big day!

Rowan of Rin
For information about what we learnt in our unit of work on Rowan of Rin by Emily Rodda, click here.

Friday Fun - 20/3/09

This week was busy and flavourful. For me, as a teacher, I was significantly challenged and stretched in the after school hours through meetings, professional development and the start of my Graduate Certificate in Educational Leadership. During school hours, I balanced normal teaching alongside assembly preparation and organisation for Harmony Day festivities.

Fun This Week...

Maths
The focus this week was on addition and subtraction. For fact practice, my group worked on adding a one-digit number to a two-digit number, and adding two-digit numbers with no re-grouping. We touched on subtraction with re-grouping, but students struggled to understand this. It is an area that we will need to work on some more, perhaps taking a step backward before progressing forward. We had some fun practising addition with a boat race game we found on Smart Kiddies - a maths teaching resource.

Harmony Day Activities
One of our students has arrived at our school from Malaysia. She is from the state of Kedah. We looked online at some facts and photographs of Kedah to get a greater sense of this student's background. We asked additional questions that came to mind. We then did a craft activity on the twin towers (Petronas Towers) in Kuala Lumpur in Malaysia. The pictures were really colourful and effective on a black background.
Other classes learnt about harmony through stories, playing soccer together, making a paper chain with their names, poetry, multicultural games and craft activities. Each year level was responsible for determining how they wanted to approach the theme and presenting what they learnt in assembly.

Assembly
In our school we aim for fortnightly whole-school assemblies, however due to other events that occur on Fridays, there are generally only three or four per term. Year levels take turns to host the assembly. The parts to an assembly are:

• a welcome
  
• an acknowledgement of country
• the singing of the national anthem and school song
• one or more class items
• the presentation of merit awards (usually 2 per class)
  
• other announcements; and
  
• the presentation of a class award for good audience behaviour

Sometimes these also include school band performances and special awards. Families are welcome to join us for these assemblies and parents make a special effort when their child is part of the hosting class.
This week's assembly was a special "Harmony Day" assembly, so as well as the normal routine we had a parade of national costumes, class presentations of Harmony Day activities and two special songs that everyone in the school had been learning. It went for longer than usual and concluded a long, hot, tiring day and so students were more restless than usual. The general feeling, however, was that it had been successful.

Eco Bus
Because our school is taking great strides in terms of Environmental Sustainability, we had three bus loads of visitors come on Friday to see our approach. The Enviro Squad was on the job, proudly explaining our recycling system and taking visitors on a tour of the school. Tim and Tina, the Trash Twins, were out and about enthusiastically promoting the appropriate use of our bins. Everyone was doing their bit in the classroom and on the playground to demonstrate what we've learnt about protecting our environment. It was a superb effort from all the teachers involved in the Sustainability Committee and a credit to the school community's commitment to Environmental Sustainability.

Readers' Theatre
Students learnt and performed a readers' theatre of the story "The Amazing Laundry Hamper" This was a fun story with a lesson to encourage children to be helpful and clean up after themselves.
We're planning a performance for parents in two weeks time. They will be able to come along to see students present readers' theatre scripts and hear the Fife and Drum band play. The performance will be in the morning, so if we find that parents are unable to attend, we may see if some of the students from Years P-2 would like to come and watch.

Rowan of Rin
To read the next installment of our Rowan of Rin literacy unit click here.

Teaching Math Facts

While teaching in New York City, I was amazed to see how easily young children can learn addition and subtraction facts through regular practice. I now use this new knowledge to train my students to add and subtract numbers more efficiently.

I used to feel that drills were not important in the teaching of Maths - that it was more important that they understand the process, than practice the drills. While I still believe that it is important for children to understand the process of addition and subtraction, I now see the value in using drills to support this.

Each week, I teach a new set of facts to my students. These may be addition facts, subtraction facts, or more recently multiplication facts. I teach my students the strategy they need, using hands on materials and demonstration models. Students then make a set of flash cards to practice these facts. For the rest of the week, my students are given a Fact Sheet to complete at the start of the Maths lesson. This worksheet contains 25 practice questions for the fact we are learning. They usually take about 6 minutes to complete this, and then if they finish early, they take out their fact cards and practice working out the answers. We go through the answers together at the end, and if there are any discrepancies, I demonstrate through illustrations on the Smart Board.

I found that by beginning with some of the simple facts, the class realises how 'easy' math facts are, and build the confidence to deal with the trickier facts later on. Adding zero, or adding one are great facts to do early on. They also like the subtracting zero, and subtracting a number from itself. I actually find that one of their most favourite sets is the doubles facts. They get very excited when they see how these connect with the multiplying by 2 facts. One of the most difficult strategies for some of my students was near doubles, or doubles + one, as it involves a couple of steps. I found that when students struggled with the concepts, they reverted to the use of their fingers to solve the equations.

I'm now a strong believer in the use of this focused drill time, for building confidence and fluency in manipulating numbers. My students now show excitement about playing with big numbers, and some of them are able to apply the strategies they have learnt to solve equations with one or more 2-digit numbers.

UPDATE: I found this great website where you can make and print out math fact sheets - Math Drills. com

(Photo by "Old Shoe Woman" at Flickr)