Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 992 · 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: a small bowl is not needed for the secret lemon message. (a) False (b) True
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) an adult with an iron (d) yeast
3. 3.⚖️ 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 keep it the same (c) we change it
4. 4.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) turmeric powder (d) a mirror
5. 5.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
6. 6.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) plugging in the iron (d) dipping the cotton bud
7. 7.True or false: cutting the lemon is a job a child can do. (a) True (b) False
8. 8.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, in the dark (d) yes, if cooled
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) a magnet
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the iron setting (d) the same paper
11. 11.🍋 Which of these steps is a job for an adult? (a) reading the message (b) cutting the lemon (c) dipping the cotton bud (d) letting the paper dry
12. 12.True or false: yeast is needed for the secret lemon message. (a) True (b) False
13. 13.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) the juice scorches first (d) paper turns lemony
14. 14.True or false: plugging in the iron is a job for an adult. (a) False (b) True
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) an adult with an iron (d) a mirror
16. 16.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
17. 17.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
18. 18.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
19. 19.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) dipping the cotton bud
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a mirror (d) lemon juice
22. 22.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) brown (d) green
23. 23.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
24. 24.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) ironing the paper
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
26. 26.True or false: letting the paper dry is a job for an adult. (a) True (b) False
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same paper
28. 28.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
29. 29.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) plugging in the iron
30. 30.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
31. 31.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) a mirror (d) a battery cell
32. 32.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
33. 33.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
34. 34.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) the ink is magnetic (d) it turned into air
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) lemon juice (d) white paper
36. 36.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) an adult with an iron (d) a cotton bud
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
39. 39.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
40. 40.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed

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