1. Monosyllabic Nouns - Plural Forms

2. Compare with Gemini (the Twins), a northern constellation.
When single syllable nouns are made plural, the consonants will either:
(1) remain unchanged
(2) double the final consonant by adding a dagesh.
For Example: Unchanged:
סוׁס
horse
סוׁסִים
horses
דָּם
blood
דָּמִים
bloods
Final consonant doubled:
עַם
people
עַמִּים
peoples
חֵץ
arrow
חִצִּים
arrows
Geminate - when the last two consonants of a word are identical, the word is a geminate.
Compare with Gemini (the Twins), a northern constellation.

3. Historically, many Hebrew words developed from three consonants.
Geminates
לֵבָב (heart)
Historically, many Hebrew words developed from three consonants.
Over time, many geminate words combined duplicate consonants.
When the duplicate consonants combined, the words became monosyllabic.
common
historical
עַם
עַמם
(people)
חֵץ
חַצץ
(arrow)
For example:
When a geminate noun is made plural, the missing duplicate consonant manifests itself as a dagesh in the remaining twin consonant.

4. Now Back to Monosyllabic Noun Plural Forms
(not just geminates)
The vowels of plural monosyllabic nouns will change under the following conditions.
1. If the noun is a geminate and the vowel is a tsere, the tsere is replaced by a hireq. For example: חֵץ (singular) חִצִּים (plural) (arrows).
2. If the final consonant is a guttural or ר and the vowel is a patakh, the vowel lengthens to a qamets. For example: הַר (singular) הָרִים (plural) (mountains)
3. If the vowel is a holem, it may change to a qibbuts. For example: חֹק (singular) חֻקִּים (plural) (statutes). However, the holem will not change to a qibbuts if it is a defective writing for וׁ.
Note Some of the Rule Breakers:
אִישׁ
man
אֲנָשִׁים
men
עִיר
city
עָרִים
cities
אִשָּׁה
woman
נָשִּׁים
women
אָב
father
אָבוֹת
fathers
רׁאשׁ
head
רָאשִׁים
heads
יוׁם
day
יָמִים
days

5. Modifications in Verbs with 2nd and 3rd Root Gutturals
Participles
Modifications in Verbs with 2nd and 3rd Root Gutturals

6. ֶת or ָה ִים וֹת כֹּרֵת Participle Review
The first vowel of an active participle is always either a holem ׂׂ or a full holem וׂ.
Masculine
Feminine
Singular
no special ending
ֶת or ָה
Plural
ִים
וֹת
כֹּרֵת
The meaning of the active participle is one of continuing action or progress.
The active participle acts like an adjective and can be used attributively or predicatively.
Remember: When an ending is added, sometimes the vowels of propretonic or pretonic syllables will reduce…
…and when those pesky gutturals are involved, things get really weird.
(gutturals are a pain)

7. Participles - 2nd and 3rd Root Gutturals
When a verb has a guttural in the 2nd root position, the vowel reduces to a composite shewa instead of a vocal shewa. For example:
Singular
Plural
Masculine
שֹׁאֵל
שֹׁאֲלִים
Feminine
שֹׁאֶלֶת
or שֹׁאֲלָה
שֹׁאֲלוֹת
The holem is preserved, so you can identify the verb as a participle.
When a verb has a ח or ע guttural consonant in the third root position, each of the vowels in the last two syllables change to a patakh in the feminine singular form. For example:
Singular
Plural
Masculine
שֹׁלֵחַ
שֹׁלְחִים
Feminine
שֹׁלַחַת or שֹׁלְחָה
שֹׁלְחוׁת

8. Participles - 2nd and 3rd Root Gutturals
When a verb has an א in the third root position, the feminine singular form maintains a tsere under the second root. The א refuses a vowel and is not pronounced. For example:
Singular
Plural
Masculine
מֹצֵא
מֹצְאִים
Feminine
מׂצֵאת
or מׂצְאָה
מׂצְאוׂת
The key: When the vowels make it hard to identify a participle, look for the first syllable holem and look for gutturals that throw off the expected vowel pattern.