Building mental math fluency
M Whitt 3:00 AM
I teach in a school with common core. The past 1 or so we have been working on standard 1.NBT.5 which states "Mentally add or subtract 10 from any 2 digit number and explain reasoning why."
So to start this off we worked with the hundreds chart. They made the connection that +10 was just the number directly below and -10 was the number directly above. We did a lot of work and practice with this.
I then used this chart and colors for tens and ones to help them make connections. I said a ten is just like 1 ten. Then I asked what is 3 tens plus 1 more ten. They said "oh 4 tens". I saw that magical light bulb go on for some of them!
I gave them many different opportunities to work with +10/-10 from a two digit number. We used dice, spinners, game boards, partner and individual games. I gave them entry tickets some days and exit tickets other days. I immediately used that data to see who need what! If one of them did not do well on the entry ticket, i pulled them that day for a small group to reinforce the skill. If it was an exit ticket they did not perform well on, I knew they would be the first one I would pull the next day.
This is a short video of one of my friends who struggled with making that connection. I had him building the numbers with tens frames. Then practicing taking a 10 away or adding a 10. He worked so hard and I was so proud of him!
I think it is super important to provide your students multiple opportunities to practice the skill. And even though the standard states to 'mentally' solve these problems, that will come in time. I think as first graders, it is important to build that fluency so they are able to make those connections to be able to solve it mentally. I also think it's important to revisit the skill many times throughout the course of the year, so they have that continued practice.
If you need some ideas or common core items, feel free to head over to my store, you may find something you like or would work in your classroom! Momma with a Teaching Mission on TpT