The purpose of this activity is to support students in understanding that the digits in a three-digit whole number refer to different sized units and that these units can be added together, just like units of one.
Model the operation with the Place Value People and record an algorithm and an equation.
60 + 30 = 90
What do you notice?
Look for students to see that 6 + 3 = 9 can be used to find 60 + 30 = 90. You might emphasise this by modelling the addition of 6 and 3 place value people in the ones column of the place value board, before drawing attention to the similarities between this model of 9 and the model of 90.
Use a calculator to model the sequence of pressing keys and to confirm the result.
Groups of ten
Hundreds
400 + 300 = 700
Hundreds and tens
240 + 300 = 540
Next steps
Practise the three key connections between words, numerals and quantities until students are fluent in solving problems without materials. This should involve the efficient use of algorithms and equations to solve problems. You might model the use of materials for the students as they solve the problem or support some students to "fold back" to the use of materials to check their working. Reinforce understanding with the use of calculator sequences. For example:
There are 530 people in the town. 240 more people come to the town for the holidays.
How many people are in the town now?
530 + 240 = 770
420 + 68 = 488
Printed from https://meaningfulmaths.nt.edu.au/mmws/nz/resource/addition-hundreds-and-tens at 9:01pm on the 26th February 2024