Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 503 · 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: turmeric powder is not needed for the secret lemon message. (a) False (b) True
2. 2.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) it turned into air (d) the paper ate it
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
5. 5.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
6. 6.True or false: reading the message is a job for an adult. (a) False (b) True
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the same paper (c) how dark the writing is (d) the kind of juice
8. 8.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it is magnetic (d) it can burn skin
9. 9.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
10. 10.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) putting the iron away (d) plugging in the iron
11. 11.True or false: letting the paper dry is a job a child can do. (a) True (b) False
12. 12.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) letting the paper dry (c) reading the message (d) dipping the cotton bud
13. 13.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) no, it stays brown (d) yes, in the dark
14. 14.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) ironing the paper (d) putting the iron away
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
16. 16.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
17. 17.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
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? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
20. 20.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) writing the message
21. 21.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
22. 22.⚖️ 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
23. 23.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) a magnet (d) a cotton bud
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
26. 26.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
27. 27.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) lemon juice (d) a cotton bud
29. 29.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
30. 30.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
32. 32.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
33. 33.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a cotton bud (d) yeast
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
36. 36.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
37. 37.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
38. 38.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) how dark the writing is (c) the kind of juice (d) the same paper
40. 40.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) cutting the lemon

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