How do you build number sense?

In the States, the idea is that you count the first 100 days of school. On the 100th day there is a big celebration, with lots of activities based on 100.

Our infant department did '100 days of school' this year, and I'm pretty sure everyone enjoyed our 'celebration' (who doesn't like to make chocolate wheeto necklaces with 100 cheerios?). But in Primary 1, we carried on counting - this picture is from yesterday, when we hit Day 177. 

In this simple addition to our morning routine, place value and reading numbers to 100 and beyond is reinforced every single day. I like using the ten frames to keep track, as we use them often during maths rotations.

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Little ones need repetition so much - especially for tricky maths concepts like place value. Luckily, they also LOVE repetition, so even though I am mightily tired of counting beyond 100, they are still tuned in!

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As part of our mental maths, and before we get to dot cards, my class and I count how many days we've been in school that year. This is a fabulous idea I've borrowed from the American teaching blogs I follow.

We don't just add a dot to our ten frame and change the number on our counting wall, though. I have magnetic Base 10 materials that we use to make the number from the previous day, and then add 1 to it. When we have the time, 4 kiddos get to be involved in this process (one to make 177, another to add 1 to it and finish the equation, one to add another dot to our counting wall and one to change the counting wall number).

I'd love to hear how you develop number sense in your classroom. And any ideas on how I can use and/or adapt this routine for older children would be very much appreciated!