# What's happening this week in Math

Oak class

Jack wants to sell his giant beans at the farmers’ market. He doesn’t think it is fair to charge

the same price for each bean since they are different sizes. He decides to charge one penny

for each cube length of the bean. He also decides he doesn’t want to take his cubes to market

each week.

So, we made a measuring strip for Jack marked off every five blocks. Since not every block is

marked off on the measuring strip, we practiced determining where the in between numbers

are. For example, 47 is between 45 and 50. It is closer to to 45 than the 50, but not as close

as where 46 is. This type of visual comparison and placement is important for working on an

open number line (no numbers marked) where we want to preserve relative magnitude and

build the concept of proportionality.

We used the measuring strips to find the total cost of multiple beans. This is the beginning of

using a number line to add double digit numbers.

We also did count arounds this week with multiples of ten. For example, a “plus 20” count

around might look like this: 8, 28, 48, 68. We also did a “plus 30”. This is building on our

work of plus 10s and helping us to make bigger, more efficient jumps in adding.

There is a simple single digit adding and subtracting game to play for homework too.

Elm Class

We started a short unit on fractions. We are only focusing on the somewhat familiar fractions

of 1/2, 1/3, 1/4, 1/6, and 1/8. We explored the idea of when the denominator increases, the

portion size decreases. We learned that “unit fractions” have a numerator of 1; these will be

part of an important strategy later on.

Sequoia Class

We continued fraction work with simplifying fractions and adding fractions using a common

denominator. But, we spent the bulk of our time adding decimals. We started our decimal

work with decimals that the kids are familiar with - money. So we did a lot of adding using

the “give and take” strategy with prices. Everything was in amounts specified to the

hundredths place.

We also briefly worked on the concept of how scaling up or down by a factor of 10 moves the

decimal place. We will work on this idea more in the next few weeks.

Redwood Class

This week we made scale drawings and used different scale ratios. We made a scale drawing

of a bedroom and its furniture with a scale of 1 cm to 20 cm. We also measured HO scale

model trains to find the actual size of various train cars and the corresponding size of Z, N, S, and O models.