Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 316 · 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.🍋 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
2. 2.⚖️ 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 kind of juice (c) the iron setting
3. 3.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
4. 4.🛟 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
5. 5.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) green (d) white
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) lemon juice (d) a small bowl
7. 7.True or false: writing the message is a job for an adult. (a) False (b) True
8. 8.True or false: ironing the paper is a job for an adult. (a) True (b) False
9. 9.⚖️ 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
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) lemon juice (d) a balloon
11. 11.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
12. 12.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a cotton bud (d) a balloon
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) turmeric powder (d) an adult with an iron
15. 15.⚖️ 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
16. 16.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) ironing the paper (d) putting the iron away
17. 17.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
18. 18.True or false: writing the message is a job a child can do. (a) True (b) False
19. 19.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) it gets darker (d) writing turns green
20. 20.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
21. 21.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
22. 22.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
23. 23.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
24. 24.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) yeast (d) lemon juice
26. 26.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) ironing the paper
27. 27.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) no, it stays brown (d) yes, in the dark
28. 28.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) writing the message (d) ironing the paper
29. 29.⚖️ 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 ironing time
30. 30.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) reading the message
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) a cotton bud (d) a balloon
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
34. 34.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
35. 35.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
36. 36.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) putting the iron away (d) cutting the lemon
37. 37.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) turmeric powder (d) white paper
39. 39.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a mirror (c) turmeric powder (d) yeast
40. 40.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True

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