Ki Teitzei- Activity suggestions related to weights & measures and fractions

A couple of suggested activities related to this week's parsha:
In last year's post, I wrote about the algebraic connection to the mitzvah (commandment) of being honest in weights and measures. Here are some suggested pre-algebra activities-

• using a balance scale, students can have different sized blocks which they need to place on the scale to figure out which is greater (heavier) and which is lesser (lighter). From there, they can investigate how many of the lesser weights it takes to balance the greater weight.
• a more difficult variation- using multiple unlabeled blocks/weights, students can work to:
•  order them from lightest to heaviest
• determine if multiples of the same block are equal to (balance) any of the other blocks
• determine if any combinations of blocks are equal to (balance) any of the other single blocks
• determine if any combinations of blocks are equal to (balance) any combinations of other blocks
• using labeled weights, students can confirm different combinations of smaller weights that should equal (or balance) with a single larger weight- for example, they should find that 2+3 is equal to (balances) a 5.
• students can then "mix and match" to find different combinations of weights that are equivalent to each other- for example, they should find that a 2+5 is equal to (balances) a 3+4.

There are many commandments (mitzvot) enumerated in this week's parsha. It has been counted that, in fact, 74 out of the 613 commandments have a basis in this parsha. Students can consider-

• What fraction of mitzvot are based in the parsha?
• Can this fraction be reduced?
• a related concept- what is the prime factorization of these two numbers? Did you know that you can quickly reduce large fractions by finding the prime factorization of both the numerator and denominator and crossing out "pairs" of common numbers that appear in both.
• a simple example- to reduce 10/15, we could say that 10 = 2x5 and 15 = 3x5; since there is a 5 in the prime factorization of both the numerator and the denominator, we can cross out both 5's, and we are left with 2/3. In this way, we have reduced 10/15 to 2/3 using prime factorization.
• another related concept- investigating common factors and identifying prime numbers (numbers that have only 2 factors- 1 and the number itself)
• What fraction of mitzvot are not based in the parsha? In other words, what's the fraction of other mitzvot that are not listed?
• Can this fraction be reduced?
• What percentage of mitzvot are listed in this parsha? What percentage of mitzvot are not listed in this parsha?
• What is the ratio of mitzvot in this parsha to the mitzvot not in this parsha?

Shoftim- Activity Suggestions related to Understanding Fractions

"This shall be the due of the Kohanim from the people, from those who perform a slaughter, whether of an ox or of a lamb/kid: he shall give the Kohen the foreleg, and the jaw, and the stomach. The first of your grain, wine, and oil, and the first of the shearing of your flock you shall give to him." ~Devarim 18:3-4

Rashi on 18:4 "The first of your grain":
"This is terumah. [Scripture] did not specify an amount regarding it, but our Rabbis established an amount regarding it: One who has a nice eye, i.e., one who is generous, give one part out of forty. One who has a bad eye, i.e., one who is miserly, gives one part out of sixty. One who is in the middle, i.e., who tends toward neither extreme, gives one part out of fifty. And they drew support from Scripture not to give less than one out of sixty, for it says, "[This is the terumah which you shall separate:] a sixth of an ephah from a chomer of wheat." A sixth of an ephah is half of a se'ah. When you give a half se'ah per kor, see now, there is one part out of sixty, for the kor is thirty se'ahs.

Activity Suggestions:
One of the most difficult conceptual aspects of fractions is that, when comparing sizes of fractional pieces, the larger the denominator (bottom number), the smaller the piece size. Once students understand fractions, they realize that this incongruence is because the denominator explains how many equal size pieces you have cut the whole into, and the more pieces you make, the smaller each piece will be. 

• With this in mind, younger students could test this by having fractional templates to cut or count and compare. Starting with the same size whole, which fractional pieces are larger and which are smaller? 1/2, 1/3, 1/4, etc. 
• Students who can make sense of this concept can extend the idea to larger number without comparing visually- compare 1/27 and 1/30, for example. And then extend to connect back to our Parsha. There, we are comparing donations of 1/40, 1/50, and 1/60. Understanding this idea, why does it make sense that 1/40 is considered generous, 1/60 is considered miserly, and 1/50 is considered average?
• Older students can look more carefully at the end section of Rashi's commentary and investigate the fractional equivalences for ephah, chomer, se'ah, and kor. Rashi's explanation indicates a comparable equivalency that relates directly to the fractions that he lists in the first part of his explanation. How do these equivalences support his explanation of the appropriate amounts to be given in donation from the first crops?

Re'eh- Activity investigations related to yearly tithings

In this week's parsha, we have two mentions of the tithings that were to be given at different times over the course of the shmita cycle. Additionally, tithings are referred to again in 3 weeks, in Parshat Ki Tavo. These three instances are looked at collectively in commentaries regarding the shmita cycle. 

• "You may not eat in your cities: the tithe of your grain, and your wine, and your oil; and the firstborn of your cattle and your flocks; all your vow offerings that you vow and your free-will offerings; and what is raised of your hand. Rather you shall eat them before Hashem, your G-d, in the place that Hashem, your G-d, will choose- you, your son, your daughter, your slave, your maidservant, and the Levite who is in your cities- and you shall rejoice before Hashem, your G-d, in your every undertaking. Beware for yourself lest you forsake the Levite, all your days in your land." ~Devarim 12:17-19
• Rashi on 12:18- regarding eating the tithings with the Levite in your city:
• Eat your first tithing together with him (1/10 portion of the crop given to Levites in each of the first 6 yrs of shemita)
• If you have no first tithe, then give from tithe for poor (1/10 of portion given to poor in third and sixth years (additional reference see 14:28-29, 26:12)
• If you have no poor tithe, then share your peace offering
• "At the end of three years you shall take out every tithe of your crop in that year and set it down within your cities. Then the Levite shall come- for he has no portion or inheritance with you- and the convert, and the orphan, and the widow who are in your cities, and they shall eat and be satisfied, in order that Hashem, your G-d, will bless you in all your handiwork that you may undertake." ~Devarim 14:28-29
• "When you have finished tithing every tithe of your produce of the third year, the year of the tithe, and you will have given to the Levite, to the convert, to the orphan, and to the widow, and they will have eaten in your cities and will have been satisfied, then you shall say before Hashem, your G-d, "I have eliminated the holy things from the house, and I have also given it to the Levite, to the convert, to the orphan, and to the widow, according to the entire commandment that you commanded me; I have not transgressed any of Your commandments, and I have not forgotten..." ~Devarim 26:12-13 (from Parshat Ki Tavo)

What were the tithings and the cycles?

• 1st tithe- 1/10 to the Levites
• 2nd tithe- 1/10 to be brought to Jerusalem and eaten there
• poor tithe- 1/10 to be given to the poor

The cycle of tithings over the shmita cycle was as follows:

Year 1- 1st tithes and 2nd tithes given

Year 2- 1st tithes and 2nd tithes given

Year 3- 1st tithes and tithes for poor given

Year 4- 1st tithes and 2nd tithes given

Year 5- 1st tithes and 2nd tithes given

Year 6- 1st tithes and tithes for poor given

Year 7- shmita year- no tithings

Activity suggestions:

• Younger children could investigate what it means to give 1/10. If you have a set-up for them to take a collection of items and divide them into ten groups, they would be donating one of those groups. The idea of 1 out of 10 might be conceptually easier for some than 1/10. In other words, for every 10 that's count out, 1 is going to be donated. 
• As children get to a point where they understand the concept of division by 10, they can practice some simple sample calculations of how much might have been donated based on a given monetary value. 
• Older children could be presented with sample scenarios of realistic incomes- some monetary based and some agriculturally based- and have them calculate projected tithings (per tithe and total donations) that families may have made over a 7 year shmita cycle. 
• Note that older students should also be able to make the connection that each 1/10 tithing would be equivalent 10% of their produce or earnings.
• It's also possible that, for some students, it would need to be clarified that all tithings were 1/10 of the total earnings; the 2nd tithing would not be calculated as 1/10 of what's left after the 1st tithing is given. This may be obvious to many, but for students who are making sense of the process, this may be a question that is unclear to them without explicit clarification.
• Extension thought- Based on these calculations, how could they think about how much the Levites had to live off of in a given year? This type of investigation could include researching information such as census information for each tribe listed in recent parshiot- if all the Levites were living off of tithings from those families, how much did they really have to live off of, per Levite family?

Eikev- An activity in comparisons and estimated measures

Last year for Parshat Eikev, I wrote about Rashi and Tanchuma's commentaries regarding the size and weight of the stone tablets that Moshe brought down with the 10 commandments inscribed on them. Their commentaries explained that despite there being differences between the two tablets, the size and weights of the two tablets were actually identical.

Thoughts on a follow-up activity:

• Last week in Parshat Va'etchanan (Devarim 5:6-18) we read the 10 commandments. These commandments were divided into the first 5, which are between man and Hashem and inscribed on the first tablet, and the second 5, which are between man and man and inscribed on the second tablet.
• If you compare, side by side, the wording, number of letters, number of characters, etc. between the two subsets of commandments, what are the actual differences between them? Which has more words, letters, characters, etc. and which has fewer? 
• Think about how you might compare the inscriptions proportionally to each other? 
• Is there a way to calculate- if I start with two 25 lb. tablets, and then inscribe in each one, is there a way to estimate how much each one should have weighed at the end? 
• Could you estimate surface area if you take a standard font and printed onto a sheet of paper- what's the ratio of print to total surface area for each tablet? What might the proportional volume differences be? What about weight differences? 
• There is a discussion in Gemara Bava Batra 14a wherein it is determined that the size of each tablet was 6 tefachim (handbreadths) high, 6 tefachim wide, and 3 tefachim deep. 
• Based on these measurements, what might the original volume of each tablet have been?
• Based on these measurements, what might the original weight of each tablet have been?
• Using estimated proportionally carved out sections from each tablet, what would one have assumed the new volumes/weights of each tablet to have been after the inscription of the commandments?
• Older students can also work through the measurement calculations from the source in Bava Batra related to the ark (where the tablets were kept) and the tablets, to see how the measurements were determined.