Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 159 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we change it (c) we measure it
2. 2.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) green (d) brown
3. 3.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) an adult with an iron (d) a cotton bud
5. 5.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
6. 6.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
7. 7.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) dipping the cotton bud (c) letting the paper dry (d) writing the message
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) yeast (d) a cotton bud
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
10. 10.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
11. 11.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) the paper ate it (d) it turned into air
12. 12.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
13. 13.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
15. 15.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words
16. 16.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
17. 17.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a battery cell (c) a mirror (d) white paper
18. 18.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the ironing time
20. 20.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) reading the message (d) ironing the paper
21. 21.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
22. 22.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) plugging in the iron (d) putting the iron away
23. 23.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) plugging in the iron (d) cutting the lemon
24. 24.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
26. 26.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
27. 27.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) plugging in the iron
28. 28.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
29. 29.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) cutting the lemon (d) plugging in the iron
30. 30.True or false: plugging in the iron is a job for an adult. (a) True (b) False
31. 31.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
32. 32.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
35. 35.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) yeast (d) a small bowl
38. 38.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
40. 40.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) letting the paper dry (d) ironing the paper

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