Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 224 · 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.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
2. 2.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) dipping the cotton bud
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
4. 4.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
5. 5.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a battery cell (d) a small bowl
6. 6.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
7. 7.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
8. 8.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
9. 9.True or false: reading the message is a job a child can do. (a) True (b) False
10. 10.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) lemon juice (c) a cotton bud (d) an adult with an iron
12. 12.True or false: ironing the paper is a job for an adult. (a) True (b) False
13. 13.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) plugging in the iron (d) dipping the cotton bud
14. 14.⚖️ 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) False (b) True
15. 15.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if shaken (d) yes, if cooled
16. 16.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
19. 19.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the same paper (d) how dark the writing is
21. 21.🛟 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
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) a cotton bud (d) a balloon
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a mirror (d) yeast
24. 24.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
25. 25.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) white paper (d) a mirror
27. 27.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) plugging in the iron (d) reading the message
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
30. 30.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
31. 31.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
32. 32.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
33. 33.True or false: writing the message is a job for an adult. (a) False (b) True
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) a small bowl (d) an adult with an iron
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a balloon (d) a small bowl
36. 36.⚖️ 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 iron setting (c) the kind of juice
37. 37.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) letting the paper dry (c) reading the message (d) writing the message
38. 38.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) dipping the cotton bud (c) plugging in the iron (d) cutting the lemon
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
40. 40.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint

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