Space marauders
This is a level 3 number activity from the Figure It Out series. It is focused on using letter symbols in an equation, and multiplying single digits by 10 and 100. A PDF of the student activity is included.
About this resource
Figure It Out is a series of 80 books published between 1999 and 2009 to support teaching and learning in New Zealand classrooms
This resource provides the teachers' notes and answers for one activity from the Figure It Out series. A printable PDF of the student activity can be downloaded from the materials that come with this resource.
Specific learning outcomes:
- Use letter symbols in an equation.
- Multiply single digits by 10 and 100.
Space marauders
Achievement objectives
NA3-4: Know how many tenths, tens, hundreds, and thousands are in whole numbers.
NA3-6: Record and interpret additive and simple multiplicative strategies, using words, diagrams, and symbols, with an understanding of equality.
Required materials
- Figure it out, Link, Number Sense, Book One, "Space marauders", page 10
See Materials that come with this resource to download:
- Space marauders activity (.pdf)
Activity
This activity will help the students to find efficient ways to add using the place value as well as the face value of the digits involved. It will also help them learn how to record equations using pronumerals and algebraic conventions.
After the students have read and understood the scoring system, work through the example of Kimberley’s first game to ensure that they have grasped the reasoning behind her recording system. This is a good opportunity to point out the algebraic convention for recording multiplication: “Kimberley’s 8S means 8 times S.” Explain that in cases such as this, we do not usually record the multiplication sign as an x because it becomes confusing when other letters are being used to represent unknown or variable numbers (because unlike + and –, x is a letter of the alphabet as well as a symbol).
The other aspect that they should explore and discuss is the way that both the positive and negative quantities that belong in the H (hits) or tens column can be recorded and calculated. In Kimberley’s first game, the hits on the space station are recorded as + (2 x –20), which is then recorded as –40 after the calculation has been done and the brackets have been removed.
1.
a. 10S + 3M + 3H
= (10 x 10) + (3 x 100) + (3 x –20)
= 100 + 300 – 60
= 340
b. 14S + 4M + 2H
= (14 x 10) + (4 x 100) + (2 x –20)
= 140 + 400 – 40
= 500
c. 18S + 4M + H
= (18 x 10) + (4 x 100) + (1 x –20)
= 180 + 400 – 20
= 560
2.
Records will vary. For example:
SSSSMSSMSSSMHSSMSSSSO (15S + 4M + H);
score: 530. Another way to get this score is an arrangement that includes 21S + 4M + 4H.
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