diff --git a/hw4-pybind/pypart.cc b/hw4-pybind/pypart.cc
index a76af678..28c76c9d 100644
--- a/hw4-pybind/pypart.cc
+++ b/hw4-pybind/pypart.cc
@@ -1,20 +1,46 @@
 #include <functional>
 #include <iostream>
 #include <pybind11/pybind11.h>
 
 #include "material_points_factory.hh"
+#include "ping_pong_balls_factory.hh"
+#include "planets_factory.hh"
+#include "csv_writer.hh"
+#include "compute_temperature.hh"
+#include "compute_gravity.hh"
+#include "compute_verlet_integration.hh"
+#include "compute_interaction.hh"
 
 namespace py = pybind11;
 
 PYBIND11_MODULE(pypart, m) {
     m.doc() = "pybind pypart plugin"; // optional docstring
 
-    py::class_<MaterialPointsFactory>(m, "MaterialPointsFactory");
-    py::class_<ParticlesFactoryInterface>(m, "ParticlesFactoryInterface");
-    py::class_<Compute>(m, "Compute");
+    // TODO:
+    // The member functions of the various classes (used in main.py) must be exposed to pybind
 
+    // Exercise 1 - Question 1, 2, 3
+    py::class_<ParticlesFactoryInterface>(m, "ParticlesFactoryInterface")
+        .def("createSimulation", py::overload_cast<const std::string, Real>(&ParticlesFactoryInterface::createSimulation),       "create simulation without functor")
+        .def("createSimulation", py::overload_cast<const std::string, Real, Func>(&ParticlesFactoryInterface::createSimulation), "create simulation with function");
 
+    py::class_<MaterialPointsFactory>(m, "MaterialPointsFactory" ); // inherits from ParticlesFactoryInterface
+    py::class_<PingPongBallsFactory>(m,  "PingPongBallsFactory"  ); // inherits from ParticlesFactoryInterface
+    py::class_<PlanetsFactory>(m,           "PlanetsFactory"     ); // inherits from ParticlesFactoryInterface
+
+
+    // Exercise 2 - Question 1
+    py::class_<Compute>(m,                  "Compute"                 );
+    py::class_<CsvWriter>(m,                "CsvWriter"               ); // inherits from Compute
+    py::class_<ComputeTemperature>(m,       "ComputeTemperature"      ); // inherits from Compute
+    py::class_<ComputeGravity>(m,           "ComputeGravity"          ); // inherits from Compute
+    py::class_<ComputeVerletIntegration>(m, "ComputeVerletIntegration"); // inherits from Compute
+    py::class_<ComputeInteraction>(m,       "ComputeInteraction"      ); // inherits from Compute
+
+
+
+    // Should we use the inheritance class in pybind??? Like below?
     //py::class_<PingPongBallsFactory, ParticlesFactoryInterface>(m, "PingPongBallsFactory");
 
 
 }