There are many math tools out there but I would hazard a guess that one of my favorites would be in just about every teacher's top 5 list. Good ol' base ten blocks.
What follows is a list of 8 activities that help students to master the skills in the 2nd grade NBT standards using nothing other than base ten blocks.
Activity #1: Comparing Numbers
Which number is greater, 23 or 32? If a student does not have a firm understanding of place value, the two numbers might as well be equal! Comparing numbers with base ten blocks allows students to see the magnitude of each digit and the difference in value across the ones and tens places.
Activity #2: Expanded Form
Expanded form is another step in understanding the value of a digit in different place values. This is also a crucial foundational skill for mental math. A student adding 234 + 10 who understands expanded form and place value would know to simply increase the "3" in the tens place to a "4" representing one more ten being added. A student who doesn't understand place value and expanded form would likely have to write 234 + 10 vertically in order to solve.
Activity #3: How Many Tens?
Given 35 ones, how many tens can you make? How many ones would still be left over? This foundational skill lays a strong framework for the traditional addition algorithm. Students will know that 6 + 7 = 13 is represented by 1 group of ten with 3 left over or ungrouped. No more 'I carry "the" one and "put down" the 3'. Students will understand exactly what is going on so that there are no careless errors due to lack of procedural understanding!
Activity #4: How Many Hundreds?
Given 46 tens, how many hundreds do you have? How many tens are left over or left ungrouped? This is a skill that 2nd graders are expected to master according to the CCLS. Students can practice and begin to see patterns and rules that always apply when grouping tens into hundreds.
Activity #5: Ten More/ Ten Less
If you asked your students to solve "Ten more than 45" would they instantly know that 55 is the answer or would they have to stop to work the answer out with pencil and paper? Ten More/Ten Less is an activity designed to allow students to start to see the patterns occurring in the tens place when another ten is added or when a ten is taken away. As students become proficient in this activity, they would be expected to move from re-counting the tens and ones each time they add or subtract and rather developing rules around the changes in the digit in the tens place.
Activity #6: 100 More/100 Less
If your students have completed activity #5, you would hope that they could make generalizations which would allow 100 More/ 100 Less to be easily understood. You'd hope. This activity allows students to make those connections in an explicit way.
Activity #7: Addition to 100
I love teaching addition with base ten blocks let me explain why:
Student explaining 53 + 29 using the traditional algorithm: First you add the numbers over here and 9 + 3 = 12 so you "put the one up" and "put down the two" then you add the 1 and 5 and 2 and get 8.
I don't know about you but putting up and putting down aren't phrases in the glossary of my math book.
Student explaining 53 + 29 using base ten blocks:
First you add the ones together. 3 ones plus 9 ones equals 12 ones. 12 ones is the same as 1 ten and 2 ones. I'll record the two in the ones column and put the group of ten in the tens column. Now I can add 5 tens, 2 tens and the new 10 that I got from the ones to get 8 tens. I'll put the 8 in the tens column. The answer is 8 tens and 2 ones or 82.
Activity #8: Addition to 1000: See Activity # 7 :)
If you are interested in the activities in this post and would like them in math center or math station form, they can be found in my TPT store.