Cleo and Corey return to the prehistoric era and have lots of fun counting stones and bones to practice their number bonds to 100. They even count the spots on a family of dinosaurs!
More resources for Autumn Block 2 Step 15.
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Discussion points for teachers
1. Help Cleo complete the bar model by drawing in the missing part and find the missing value using your knowledge of bonds to 100.
Discuss which values we already know. Discuss the total we are trying to reach. Discuss how we can work out the missing value.
2. How many bones have they got altogether so far? How many bones does Cleo need to have found to make a total of 100?
Discuss how many bones were in the initial pile. Discuss how many bones Corey has found. Discuss what the total of these two values is. Discuss how we can work out the missing value. Discuss how this would look in a bar model.
18 + 36 = 54
3. How many pieces of volcanic rock could Cleo have now? How many pieces would Corey have to find to make a total of 100?
Discuss all the possible amounts of volcanic rock that Cleo could have. Discuss how much volcanic rock Corey would have to find for each of these amounts to make a total of 100.
Cleo could have 48, 47, 46, 45 or 44 pieces of volcanic rock.
Corey would have to find either 52, 53, 54, 55 or 56 pieces of volcanic rock to make a total of 100.
4. Complete the part-whole model to help Cleo and Corey work out how many spots the baby dinosaurs must have, if between all four, there are one hundred spots. How many could each baby have?
Discuss where the given value has come from. Discuss what the other value would have to be. Discuss the different ways this value could be partitioned. Discuss what the value in the whole must be. This question is open-ended for the children to explore.
Various answers, for example:
Optional discussion points:
How can we use our knowledge of bonds to 10 to help us with bonds to 100?
National Curriculum Objectives
Mathematics Year 2: (2C1) Recall and use addition and subtraction facts to 20 fluently, and derive and use related facts up to 100
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