Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 165 · 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.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
2. 2.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it can burn skin (d) it is magnetic
3. 3.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
4. 4.⚖️ 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
5. 5.True or false: cutting the lemon is a job a child can do. (a) True (b) False
6. 6.⚖️ 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
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) rub your eyes (d) lick your fingers
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
9. 9.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
10. 10.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
11. 11.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) white (d) green
12. 12.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
13. 13.🍋 Which of these steps is a job for an adult? (a) reading the message (b) cutting the lemon (c) writing the message (d) letting the paper dry
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) a magnet
15. 15.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) yes, if shaken (d) no, it stays brown
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) an adult with an iron (d) turmeric powder
17. 17.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
18. 18.True or false: cutting the lemon is a job for an adult. (a) False (b) True
19. 19.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) plugging in the iron
20. 20.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) the iron is brown (d) heat adds colour
21. 21.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) turmeric powder (c) a mirror (d) yeast
22. 22.⚖️ 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 iron setting
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) yeast (d) lemon juice
24. 24.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
25. 25.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a small bowl (c) an adult with an iron (d) lemon juice
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a mirror (d) lemon juice
28. 28.⚖️ 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 measure it (c) we keep it the same
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) a cotton bud (d) an adult with an iron
30. 30.⚖️ 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 keep it the same (c) we change it
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) a mirror (d) turmeric powder
32. 32.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) ironing the paper (d) cutting the lemon
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the iron setting (c) how dark the writing is (d) the same paper
34. 34.True or false: white paper is needed for the secret lemon message. (a) False (b) True
35. 35.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a battery cell (d) a small bowl
37. 37.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) reading the message (d) ironing the paper
38. 38.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
39. 39.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) a magnet (d) lemon juice

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