diff --git a/src/fiber_package/entity/person.py b/src/fiber_package/entity/person.py
index 4d05c34..eeabbeb 100644
--- a/src/fiber_package/entity/person.py
+++ b/src/fiber_package/entity/person.py
@@ -1,4 +1,4 @@
-from pydantic import model_validator, EmailStr, computed_field, field_serializer
+from pydantic import model_validator, EmailStr, field_serializer
 from typing import Self, Literal
 from datetime import date
 
@@ -31,7 +31,7 @@ class PersonModel(FiberBaseModel):
         if self.date_of_birth is None:
             return False
         if ref_date is None:
-            ref_data = date.today()
+            ref_date = date.today()
         age = ( ref_date.year - self.date_of_birth.year
                 - ( (ref_date.month, ref_date.day)
                     < (self.date_of_birth.month, self.date_of_birth.day) )
diff --git a/src/fiber_package/event/activity.py b/src/fiber_package/event/activity.py
new file mode 100644
index 0000000..c0aeae7
--- /dev/null
+++ b/src/fiber_package/event/activity.py
@@ -0,0 +1,75 @@
+from typing import Literal, Self
+from pydantic import model_validator
+
+from datetime import datetime
+
+from .communication import CommunicationModel
+from .submodels import ActivityPaymentInfo
+from .enums import CommunicationCategory
+
+from fiber_package.refs import SignupRefList
+from fiber_package.signup.signup import SignupModel
+from fiber_package.signup.util import validate_answer
+from fiber_package.signup.enums import is_question_category
+
+from fiber_package.signup.element.form_base_question import FormBaseQuestion
+
+from fiber_package.signup.element.types import FormElementUnion, FormTextUnion
+
+class ActivityModel(CommunicationModel):
+    category: Literal[CommunicationCategory.activity]
+
+    slug: str
+    # unique short name used in the public URL
+
+    start_time: datetime
+    end_time: datetime
+
+    payment_info: ActivityPaymentInfo | None = None
+
+    form: list[FormElementUnion]
+
+    signups: SignupRefList = SignupRefList([], "signup")
+
+    # TODO: see Felt 'activiteiten' DB schema. Things like:
+    # email, target group, maximal attendees ....
+
+    @model_validator(mode='after')
+    def check_end_after_start(self) -> Self:
+        if self.end_time < self.start_time:
+            raise ValueError("End time cannot be earlier than start time")
+        return self
+
+    def validate_signup_form(self, signup: SignupModel) -> None:
+        required = set()
+        answerable = set()
+
+        question_dict: dict[str, FormBaseQuestion] = {}
+
+        for element in self.form:
+            if not is_question_category(element.category):
+                continue
+            # so we know it is istance of FormBaseQuestion
+            answerable.add(element.name)
+            if element.required:
+                required.add(element.name)
+            question_dict[element.name] = element
+
+        answers = signup.answers
+        for answer in answers:
+            q_name = answer.question_name
+            if q_name not in answerable:
+                raise ValueError(
+                    f"Form contains answer to "
+                    f"non-existing question {q_name}."
+                )
+            answerable.remove(q_name)
+            if answer.question_name in required:
+                required.remove(q_name)
+
+            question = question_dict[q_name]
+            validate_answer(question, answer)
+
+
+        if len(required) > 0:
+            raise ValueError("Form does not answer all required questions.")
diff --git a/src/fiber_package/event/communication.py b/src/fiber_package/event/communication.py
new file mode 100644
index 0000000..d5b17ee
--- /dev/null
+++ b/src/fiber_package/event/communication.py
@@ -0,0 +1,44 @@
+from pydantic import Field, HttpUrl
+
+from fiber_package.base import FiberBaseModel
+
+from .enums import CommunicationCategory
+
+'''
+A "communication" is a piece of communication/promotion to be shared with
+members, which may appear on the website and in the weekly mailing.
+'''
+class CommunicationModel(FiberBaseModel):
+    category: CommunicationCategory
+
+    name_en: str
+    name_nl: str
+
+    association_tags: list[str] = Field(default_factory=list)
+    # list of associations this communication belongs to
+
+    subtitle_en: str
+    subtitle_nl: str
+    # subtitles currently (2026) appear only in the table of contents in the
+    # weekly mailing; they are meant to be a short catchy flavour text
+
+    description_en: str
+    description_nl: str
+
+    image: HttpUrl | None = None
+    # often, a poster comes associated with a communication (in particular if
+    # it's an activity). In that case, the poster is uploaded to the cloud and
+    # the share link is attached to the communication
+    # TODO: potentially rethink the way images are attached to communications
+
+    visibility: bool
+    # should this communication be shown to members at all? Useful for
+    # temporarily hiding a communication
+
+    only_members: bool
+    # is this communication only visible to members? This refers to visibility
+    # on the website, i.e. is this only visible to visitors who are logged in?
+
+    archived: bool
+    # an archived communication cannot be edited, only viewed for future
+    # reference
diff --git a/src/fiber_package/event/enums.py b/src/fiber_package/event/enums.py
new file mode 100644
index 0000000..84682d2
--- /dev/null
+++ b/src/fiber_package/event/enums.py
@@ -0,0 +1,10 @@
+from enum import StrEnum
+
+'''
+The category is only used to place the communication correctly in the weekly
+mailing and the board-website, it is not visible (or relevant) to readers
+'''
+class CommunicationCategory(StrEnum):
+    announcement = "announcement"
+    news = "news"
+    activity = "activity"
diff --git a/src/fiber_package/event/notes.txt b/src/fiber_package/event/notes.txt
new file mode 100644
index 0000000..f19315c
--- /dev/null
+++ b/src/fiber_package/event/notes.txt
@@ -0,0 +1,48 @@
+Okay some ideas:
+
+We want a modular system.
+A signup form = list of signup questions
+A signup = list of signup answers
+
+
+Examples of questions:
+* Dietary restrictions
+* Insurance info
+* Pick option from list
+* Team (interesting one, as people can also make new teams)
+
+
+class SignupQuestion
+--> SignupQuestionDiet, SignupQuestionInsurance, SignupQuestionOption ....
+Questions differentiate through enum question_type
+Questions can have parameters like Option
+
+--------------
+
+Every SignupQuestionXYZ has a SignupAnswerXYZ
+
+
+An activity consists of:
+* usual event stuff, email, max_attendees, ....
+* a slug!
+* dict of SignupQuestions
+* list of QuestionOrder
+
+A signup then consists of:
+* ActivityRef (what activity)
+* EntityRef (who signed up)
+* optional payment_id
+* optional is_reserve
+* optional confirmed (true if paid)
+* dict of SignupAnswers
+
+--------------
+
+When saving a signup, we check:
+* get activity
+* is person allowed to sign up?
+* do we have enough signup answers
+* for every answer: does answer validate type of question?
+
+
+
diff --git a/src/fiber_package/event/submodels.py b/src/fiber_package/event/submodels.py
new file mode 100644
index 0000000..ffc6f30
--- /dev/null
+++ b/src/fiber_package/event/submodels.py
@@ -0,0 +1,14 @@
+from decimal import Decimal
+from typing import Annotated
+
+from pydantic import BaseModel, Field
+
+class ActivityPaymentInfo(BaseModel):
+    contribution: Annotated[
+        Decimal, Field(decimal_places=2, ge=0)
+    ]
+    nnv_contribution: Annotated[
+        Decimal | None, Field(None, decimal_places=2, ge=0)
+    ] = None
+
+
diff --git a/src/fiber_package/refs.py b/src/fiber_package/refs.py
index 6032df2..e74312d 100644
--- a/src/fiber_package/refs.py
+++ b/src/fiber_package/refs.py
@@ -11,7 +11,9 @@ CollectionName = Literal[
     "entity",
     "committee",
     "committee_edition",
-    "guild"
+    "guild",
+    "signup",
+    "event"
 ]
 
 C = TypeVar("C", bound=str)
@@ -47,3 +49,13 @@ CommitteeEditionRefList = RefList[Literal["committee_edition"]]
 
 GuildRef = Ref[Literal["guild"]]
 GuildRefList = RefList[Literal["guild"]]
+
+SignupRef = Ref[Literal["signup"]]
+SignupRefList = RefList[Literal["signup"]]
+
+CommunicationRef = Ref[Literal["event"]]
+CommunicationRefList = Ref[Literal["event"]]
+
+# Activities are stored in the collection of communications
+ActivityRef = CommunicationRef
+ActivityRefList = CommunicationRefList
diff --git a/src/fiber_package/signup/answer/answer_base.py b/src/fiber_package/signup/answer/answer_base.py
new file mode 100644
index 0000000..533793a
--- /dev/null
+++ b/src/fiber_package/signup/answer/answer_base.py
@@ -0,0 +1,8 @@
+from pydantic import BaseModel, ConfigDict
+from fiber_package.signup.enums import FormQuestionCategory
+
+class AnswerBase(BaseModel):
+    model_config = ConfigDict(extra='allow')
+
+    category: FormQuestionCategory
+    question_name: str
diff --git a/src/fiber_package/signup/answer/answer_checkmarks.py b/src/fiber_package/signup/answer/answer_checkmarks.py
new file mode 100644
index 0000000..95c3842
--- /dev/null
+++ b/src/fiber_package/signup/answer/answer_checkmarks.py
@@ -0,0 +1,9 @@
+from typing import Literal
+
+from .answer_base import AnswerBase
+from fiber_package.signup.enums import FormElementCategory
+
+class AnswerCheckmarks(AnswerBase):
+    category: Literal[FormElementCategory.checkmarks]
+
+    answer_list: list[bool]
diff --git a/src/fiber_package/signup/answer/answer_open_questions.py b/src/fiber_package/signup/answer/answer_open_questions.py
new file mode 100644
index 0000000..b399dbb
--- /dev/null
+++ b/src/fiber_package/signup/answer/answer_open_questions.py
@@ -0,0 +1,9 @@
+from typing import Literal
+
+from .answer_base import AnswerBase
+from fiber_package.signup.enums import FormElementCategory
+
+class AnswerOpenQuestions(AnswerBase):
+    category: Literal[FormElementCategory.open_questions]
+
+    answer_list: list[str]
diff --git a/src/fiber_package/signup/answer/types.py b/src/fiber_package/signup/answer/types.py
new file mode 100644
index 0000000..8d31d00
--- /dev/null
+++ b/src/fiber_package/signup/answer/types.py
@@ -0,0 +1,11 @@
+from typing import Annotated
+
+from pydantic import Field
+
+from .answer_open_questions import AnswerOpenQuestions
+from .answer_checkmarks import AnswerCheckmarks
+
+AnswerUnion = Annotated[
+    AnswerOpenQuestions | AnswerCheckmarks,
+    Field(discriminator="category")
+]
diff --git a/src/fiber_package/signup/element/form_base_question.py b/src/fiber_package/signup/element/form_base_question.py
new file mode 100644
index 0000000..c0c1942
--- /dev/null
+++ b/src/fiber_package/signup/element/form_base_question.py
@@ -0,0 +1,11 @@
+from .form_element import FormElement
+from fiber_package.signup.enums import FormQuestionCategory
+
+class FormBaseQuestion(FormElement):
+    category: FormQuestionCategory
+
+    required: bool
+
+    title: str | None = None
+    pretext: str | None = None
+    posttext: str | None = None
diff --git a/src/fiber_package/signup/element/form_base_text.py b/src/fiber_package/signup/element/form_base_text.py
new file mode 100644
index 0000000..1cffa93
--- /dev/null
+++ b/src/fiber_package/signup/element/form_base_text.py
@@ -0,0 +1,5 @@
+from .form_element import FormElement
+from fiber_package.signup.enums import FormTextCategory
+
+class FormBaseText(FormElement):
+    category: FormTextCategory
diff --git a/src/fiber_package/signup/element/form_checkmarks.py b/src/fiber_package/signup/element/form_checkmarks.py
new file mode 100644
index 0000000..d0af93c
--- /dev/null
+++ b/src/fiber_package/signup/element/form_checkmarks.py
@@ -0,0 +1,29 @@
+from typing import Literal
+from pydantic import BaseModel
+
+from .form_base_question import FormBaseQuestion
+from fiber_package.signup.enums import FormElementCategory
+
+from fiber_package.signup.answer.answer_checkmarks import AnswerCheckmarks
+
+class CheckmarkQuestion(BaseModel):
+    question_en: str
+    question_nl: str
+    default: bool = False
+
+class FormCheckmarks(FormBaseQuestion):
+    category: Literal[FormElementCategory.checkmarks]
+
+    questions: list[CheckmarkQuestion]
+
+    def validate_answer(self, answer: AnswerCheckmarks) -> None:
+        if answer.question_name != self.name:
+            raise ValueError("Answer question name does not match.")
+
+        answer_list = answer.answer_list
+        if len(answer_list) != len(self.questions):
+            raise ValueError("Length of answer question list does not match.")
+
+
+
+
diff --git a/src/fiber_package/signup/element/form_element.py b/src/fiber_package/signup/element/form_element.py
new file mode 100644
index 0000000..b68be56
--- /dev/null
+++ b/src/fiber_package/signup/element/form_element.py
@@ -0,0 +1,8 @@
+from pydantic import BaseModel, ConfigDict
+from fiber_package.signup.enums import FormElementCategory
+
+class FormElement(BaseModel):
+    model_config = ConfigDict(extra='allow')
+
+    category: FormElementCategory
+    name: str
diff --git a/src/fiber_package/signup/element/form_open_questions.py b/src/fiber_package/signup/element/form_open_questions.py
new file mode 100644
index 0000000..c0429a8
--- /dev/null
+++ b/src/fiber_package/signup/element/form_open_questions.py
@@ -0,0 +1,34 @@
+from typing import Literal
+from pydantic import BaseModel
+
+from .form_base_question import FormBaseQuestion
+from fiber_package.signup.enums import FormElementCategory
+
+from fiber_package.signup.answer.answer_open_questions import AnswerOpenQuestions
+
+class OpenQuestion(BaseModel):
+    question_en: str
+    question_nl: str
+
+    explanation_en: str
+    explanation_nl: str
+
+    placeholder_en: str = ""
+    placeholder_nl: str = ""
+
+class FormOpenQuestions(FormBaseQuestion):
+    category: Literal[FormElementCategory.open_questions]
+
+    questions: list[OpenQuestion]
+
+    def validate_answer(self, answer: AnswerOpenQuestions) -> None:
+        if answer.question_name != self.name:
+            raise ValueError("Answer question name does not match.")
+
+        answer_list = answer.answer_list
+        if len(answer_list) != len(self.questions):
+            raise ValueError("Length of answer question list does not match.")
+
+
+
+
diff --git a/src/fiber_package/signup/element/form_text.py b/src/fiber_package/signup/element/form_text.py
new file mode 100644
index 0000000..991e42b
--- /dev/null
+++ b/src/fiber_package/signup/element/form_text.py
@@ -0,0 +1,9 @@
+from typing import Literal
+
+from .form_element import FormElement
+from fiber_package.signup.enums import FormElementCategory
+
+class FormText(FormElement):
+    category: Literal[FormElementCategory.text_piece]
+
+    text: str
diff --git a/src/fiber_package/signup/element/form_title.py b/src/fiber_package/signup/element/form_title.py
new file mode 100644
index 0000000..d300c64
--- /dev/null
+++ b/src/fiber_package/signup/element/form_title.py
@@ -0,0 +1,9 @@
+from typing import Literal
+
+from .form_element import FormElement
+from fiber_package.signup.enums import FormElementCategory
+
+class FormTitle(FormElement):
+    category: Literal[FormElementCategory.title_text]
+
+    title: str
diff --git a/src/fiber_package/signup/element/types.py b/src/fiber_package/signup/element/types.py
new file mode 100644
index 0000000..76c8a36
--- /dev/null
+++ b/src/fiber_package/signup/element/types.py
@@ -0,0 +1,23 @@
+from typing import Annotated
+
+from pydantic import Field
+
+from .form_open_questions import FormOpenQuestions
+from .form_checkmarks import FormCheckmarks
+from .form_text import FormText
+from .form_title import FormTitle
+
+FormTextUnion = Annotated[
+    FormText | FormTitle,
+    Field(discriminator="category")
+]
+
+FormQuestionUnion = Annotated[
+    FormOpenQuestions | FormCheckmarks,
+    Field(discriminator="category")
+]
+
+FormElementUnion = Annotated[
+    FormTextUnion | FormQuestionUnion,
+    Field(discriminator="category")
+]
diff --git a/src/fiber_package/signup/enums.py b/src/fiber_package/signup/enums.py
new file mode 100644
index 0000000..5cb289d
--- /dev/null
+++ b/src/fiber_package/signup/enums.py
@@ -0,0 +1,24 @@
+from enum import StrEnum
+from typing import Literal, get_args
+
+'''
+This category is used to differentiate types of form elements
+'''
+class FormElementCategory(StrEnum):
+    text_piece = "text_piece"
+    title_text = "title_text"
+    open_questions = "open_questions"
+    checkmarks = "checkmarks"
+
+FormQuestionCategory = Literal[
+    FormElementCategory.open_questions,
+    FormElementCategory.checkmarks
+]
+
+FormTextCategory = Literal[
+    FormElementCategory.text_piece,
+    FormElementCategory.title_text
+]
+
+def is_question_category(category: FormElementCategory) -> bool:
+    return category in get_args(FormQuestionCategory)
diff --git a/src/fiber_package/signup/howto-add-new-question.txt b/src/fiber_package/signup/howto-add-new-question.txt
new file mode 100644
index 0000000..7c931ae
--- /dev/null
+++ b/src/fiber_package/signup/howto-add-new-question.txt
@@ -0,0 +1,13 @@
+In order to add a new question type you need to:
+
+1) Make a new tag in enums.py
+2) add it to the list of question tags
+3) Create the FormXXX in element
+4) Create the AnswerXXX in answer
+5) Add it to the answer union type in answer.types
+6) Add it to the question union type in element.types 
+Tip: run ./pre-commit to run the typechecker to see if you got your imports right!
+7) Add it to fiber-django
+    6a) Add it to the process_question function event/util.py
+    6b) Add it to core/templates/form 
+    6c) Add it to the form page (currently dlfsite/templates/testing/form.html)
\ No newline at end of file
diff --git a/src/fiber_package/signup/notes.txt b/src/fiber_package/signup/notes.txt
new file mode 100644
index 0000000..7df7049
--- /dev/null
+++ b/src/fiber_package/signup/notes.txt
@@ -0,0 +1,65 @@
+Felt has sjablonen, stored in config
+
+sjablonen.(name) has fields:
+* naam_nl = default name
+* naam_en = ...
+* info = used in the sjabloon overview
+* types (array_keys ???)
+* parameters = dict of parameters & type
+* parametes_beschrijving = description of parameters
+* parameters_sample = default values of all parameters
+
+On /activiteiten/bewerk we have a list of if statements
+It groups the answers by type
+* choises, feedback, teams, dinner, shirtsizes, nnv, 
+* public transport, reserve list, signups list
+
+* activites store their "types" as bitmask (1 = medisch, 2 = thuisfront ...)
+* stored in models\Parameter  
+* list of parameter datatypes, 
+
+Why is everything so builtin ?! Crazy. 
+
+List of question types:
+* medical --> alergies, meds, extra info
+* thuisfront --> name contact, email contact, phone #1, phone #2
+* shirtsize --> pick enum from XXS, XS, S, M, L, XL, XXL
+* identification --> document type, document number, expiry date, ...
+* nnv --> state (notmember, later, member) & nnv number
+* food --> joins for the meal (true/false), diet (text), vegetarian (t/f)
+* public transport --> enum (no, week-only, weekend-only)
+* travel / zorgverzekering --> verzekeraar, polisnummer, noodnummer, type (zorg of reis)
+* questions --> parameter_id, slot, answer
+* choices --> parameter_id, slot, choice
+* feedback --> feedabck (str)
+* team --> teamname (str)
+
+
+
+omg it is TERRIBLE. In Silk every sjabloon has its OWN template ?!
+so much work yikes
+
+Example for the "Studiereis" sjabloon:
+* Some text (incl deadline) --> we can refer to variables and use HTML!
+* Header (your signup is coupled to your current account!)
+* Health insurance (+ text)
+* Medical information (+ text)
+* Home stayers (+text & checkmark about International Office)
+* Identification (+text)
+* NNV (+text)
+* T-shirt 
+* OV
+* Feedback
+
+Pattern:
+* (title) (prefix text) item (suffix text)
+Then possibly also:
+* title-items & text-items
+
+-------------
+
+Ideas:
+* Modular system!
+* Create template activities (by creating activity, store as template & then delete?)
+
+* Combine complicated questions into custom question (see all above)
diff --git a/src/fiber_package/signup/signup.py b/src/fiber_package/signup/signup.py
new file mode 100644
index 0000000..8690685
--- /dev/null
+++ b/src/fiber_package/signup/signup.py
@@ -0,0 +1,16 @@
+from typing import Literal
+
+from fiber_package.base import FiberBaseModel
+from fiber_package.refs import EntityRef, ActivityRef
+
+from fiber_package.signup.answer.types import AnswerUnion
+
+class SignupModel(FiberBaseModel):
+    collection_name: Literal["signup"] = "signup"
+
+    attendee: EntityRef
+    activity: ActivityRef
+
+    answers: list[AnswerUnion]
+
+    # TODO: signed_up, is_reserve, payment, confirmed, ....
diff --git a/src/fiber_package/signup/util.py b/src/fiber_package/signup/util.py
new file mode 100644
index 0000000..91d037f
--- /dev/null
+++ b/src/fiber_package/signup/util.py
@@ -0,0 +1,18 @@
+from fiber_package.signup.element.form_base_question import FormBaseQuestion
+from fiber_package.signup.element.form_open_questions import FormOpenQuestions
+
+from fiber_package.signup.answer.answer_base import AnswerBase
+from fiber_package.signup.enums import FormElementCategory
+
+from fiber_package.signup.answer.answer_open_questions import AnswerOpenQuestions
+
+def validate_answer(question: FormBaseQuestion, answer: AnswerBase) -> None:
+    if question.category != answer.category:
+        raise ValueError("Question and answer category do not match!")
+
+    if question.category == FormElementCategory.open_questions:
+        question_val = FormOpenQuestions.model_validate(question.model_dump())
+        answer_val = AnswerOpenQuestions.model_validate(answer.model_dump())
+        question_val.validate_answer(answer_val)
+
+    # TODO: implement