Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 340 · 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 battery cell is needed for the secret lemon message. (a) True (b) False
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
3. 3.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
4. 4.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the paper ate it (d) the ink is magnetic
5. 5.🧺 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) a battery cell (d) lemon juice
6. 6.⚖️ 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 ironing time (c) the iron setting (d) the kind of juice
7. 7.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
8. 8.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the iron setting (c) the kind of juice (d) how dark the writing is
10. 10.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
11. 11.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) blue words (d) dark brown words
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) white paper (d) a battery cell
13. 13.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
14. 14.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) a magnet (d) white paper
16. 16.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
17. 17.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
18. 18.True or false: writing the message is a job a child can do. (a) False (b) True
19. 19.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if cooled (d) yes, if shaken
20. 20.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
21. 21.🍋 Which of these steps is a job a child can do? (a) reading the message (b) ironing the paper (c) putting the iron away (d) cutting the lemon
22. 22.True or false: putting the iron away is a job for an adult. (a) False (b) True
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) an adult with an iron (d) turmeric powder
24. 24.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a balloon (d) lemon juice
26. 26.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
27. 27.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a small bowl (c) white paper (d) an adult with an iron
29. 29.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) yeast (d) a mirror
30. 30.⚖️ 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
31. 31.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) rub your eyes (d) skip washing
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
33. 33.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
34. 34.⚖️ 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) the ironing time (c) how dark the writing is
35. 35.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
36. 36.⚖️ 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) the same paper (c) how dark the writing is
37. 37.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) green (d) white
38. 38.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
39. 39.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) putting the iron away (d) plugging in the iron
40. 40.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed

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