diff --git a/exercise-instructions.md b/exercise-instructions.md
index c055ede..cff2c92 100644
--- a/exercise-instructions.md
+++ b/exercise-instructions.md
@@ -3,7 +3,7 @@
 Download (clone) the exercise material with
 
 ```bash
-$ git clone https://github.com/csc-training/hpc-python.git
+$ git clone -b mooc https://github.com/csc-training/hpc-python.git
 ```
 The external Python packages can be installed with **pip** by using the provided 
 [requirements.txt](requirements.txt) file. In CSC classroom this can be done 
diff --git a/numpy/broadcast-rotation/README.md b/numpy/broadcast-rotation/README.md
index 03aac56..c043e6e 100644
--- a/numpy/broadcast-rotation/README.md
+++ b/numpy/broadcast-rotation/README.md
@@ -11,7 +11,7 @@ R =
 \end{pmatrix}
 --->
 
-![img](http://quicklatex.com/cache3/9c/ql_ee4015bef241c06a5119104118f9a19c_l3.png)
+![img](../img/rotation-matrix.png)
 
 where θ is the angle of rotation (in radians). Start from the x-y coordinates
 in the file points_circle.dat and rotate them by 90°. Utilize broadcasting for
diff --git a/numpy/finite-difference/README.md b/numpy/finite-difference/README.md
index 792f139..777ab47 100644
--- a/numpy/finite-difference/README.md
+++ b/numpy/finite-difference/README.md
@@ -9,7 +9,7 @@ as:
 f'(x_i) = \frac{f(x_i + \Delta x)- f(x_i - \Delta x)}{2 \Delta x}
 --->
 
-![img](https://quicklatex.com/cache3/0a/ql_d10c99a114e66c7ed0535e0aeb041d0a_l3.png)
+![img](../img/finite-difference.png)
 
 Construct 1D Numpy array containing the values of xi in the interval [0,π/2]
 with spacing Δx=0.1. Evaluate numerically the derivative of **sin** in this
diff --git a/numpy/heat-equation/README.md b/numpy/heat-equation/README.md
index 5f14513..96b30be 100644
--- a/numpy/heat-equation/README.md
+++ b/numpy/heat-equation/README.md
@@ -5,7 +5,7 @@ Heat (or diffusion) equation is
 <!-- Equation
 \frac{\partial u}{\partial t} = \alpha \nabla^2 u
 --> 
-![img](https://quicklatex.com/cache3/d2/ql_b3f6b8bdc3a8862c73c5a97862afb9d2_l3.png)
+![img](../img/heat-equation.png)
 
 where **u(x, y, t)** is the temperature field that varies in space and time,
 and α is thermal diffusivity constant. The two dimensional Laplacian can be
@@ -17,7 +17,7 @@ discretized with finite differences as
  &+ \frac{u(i,j-1)-2u(i,j)+u(i,j+1)}{(\Delta y)^2}
 \end{align*}
 --> 
-![img](https://quicklatex.com/cache3/2d/ql_59f49ed64dbbe76704e0679b8ad7c22d_l3.png)
+![img](../img/nabla.png)
 
 Given an initial condition (u(t=0) = u0) one can follow the time dependence of
 the temperature field with explicit time evolution method:
@@ -25,14 +25,14 @@ the temperature field with explicit time evolution method:
 <!-- Equation
 u^{m+1}(i,j) = u^m(i,j) + \Delta t \alpha \nabla^2 u^m(i,j) 
 --> 
-![img](https://quicklatex.com/cache3/9e/ql_9eb7ce5f3d5eccd6cfc1ff5638bf199e_l3.png)
+![img](../img/heat-time-propagation.png)
 
 Note: Algorithm is stable only when
 
 <!-- Equation
 \Delta t < \frac{1}{2 \alpha} \frac{(\Delta x \Delta y)^2}{(\Delta x)^2 (\Delta y)^2}
 -->
-![img](https://quicklatex.com/cache3/d1/ql_0e7107049c9183d11dbb1e81174280d1_l3.png)
+![img](../img/heat-stability.png)
 
 Implement two dimensional heat equation with NumPy using the initial
 temperature field in the file [bottle.dat](bottle.dat) (the file consists of a
diff --git a/numpy/img/finite-difference.png b/numpy/img/finite-difference.png
new file mode 100644
index 0000000..62e3a31
Binary files /dev/null and b/numpy/img/finite-difference.png differ
diff --git a/numpy/img/heat-equation.png b/numpy/img/heat-equation.png
new file mode 100644
index 0000000..2cae86b
Binary files /dev/null and b/numpy/img/heat-equation.png differ
diff --git a/numpy/img/heat-stability.png b/numpy/img/heat-stability.png
new file mode 100644
index 0000000..9a418e2
Binary files /dev/null and b/numpy/img/heat-stability.png differ
diff --git a/numpy/img/heat-time-propagation.png b/numpy/img/heat-time-propagation.png
new file mode 100644
index 0000000..ec2e024
Binary files /dev/null and b/numpy/img/heat-time-propagation.png differ
diff --git a/numpy/img/nabla.png b/numpy/img/nabla.png
new file mode 100644
index 0000000..6a0cc87
Binary files /dev/null and b/numpy/img/nabla.png differ
diff --git a/numpy/img/rieman-sum1.png b/numpy/img/rieman-sum1.png
new file mode 100644
index 0000000..ab919d1
Binary files /dev/null and b/numpy/img/rieman-sum1.png differ
diff --git a/numpy/img/rieman-sum2.png b/numpy/img/rieman-sum2.png
new file mode 100644
index 0000000..eb07078
Binary files /dev/null and b/numpy/img/rieman-sum2.png differ
diff --git a/numpy/img/rotation-matrix.png b/numpy/img/rotation-matrix.png
new file mode 100644
index 0000000..b1d6168
Binary files /dev/null and b/numpy/img/rotation-matrix.png differ
diff --git a/numpy/integration/README.md b/numpy/integration/README.md
index de2993e..857f76e 100644
--- a/numpy/integration/README.md
+++ b/numpy/integration/README.md
@@ -7,7 +7,7 @@ sum
 S = \int_a^b f(x) dx = \sum_{i=1}^n f(x'_i) \Delta x
 --->
 
-![img](https://quicklatex.com/cache3/e2/ql_30419670e67bc2b3d039e8a9d8653de2_l3.png)
+![img](../img/rieman-sum1.png)
 
 with
 
@@ -15,7 +15,7 @@ with
 x'_i = (x_i + x_{i-1}) / 2; x_0 = a, x_n = b
 --->
 
-![img](https://quicklatex.com/cache3/09/ql_f124fd5c831e873c6abd41160fae2d09_l3.png)
+![img](../img/rieman-sum2.png)
 
 Calculate the integral in the interval [0,π/2] and investigate how much the
 Riemann sum of **sin** differs from 1.0. Avoid `for` loops. Investigate also