Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 788 · 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 a magnet for the secret lemon message? (a) needed (b) not needed
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) a small bowl (d) lemon juice
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) how dark the writing is (c) the same paper (d) the ironing time
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) a balloon (d) lemon juice
5. 5.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) rub your eyes (d) wash your hands
6. 6.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
7. 7.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a mirror (c) an adult with an iron (d) white paper
9. 9.⚖️ 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
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) a battery cell (d) a small bowl
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) turmeric powder (d) white paper
12. 12.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
13. 13.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
14. 14.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) musical (d) chemical
15. 15.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it can burn skin (d) it is sticky
16. 16.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) heat adds colour (d) the iron is brown
17. 17.⚖️ 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
18. 18.⚖️ 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
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) lemon juice (d) white paper
20. 20.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a battery cell (d) an adult with an iron
21. 21.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
22. 22.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
23. 23.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) the youngest child (d) any child
24. 24.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
25. 25.⚖️ 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
26. 26.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
27. 27.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) putting the iron away (d) writing the message
28. 28.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) lemon juice (d) turmeric powder
30. 30.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) the paper floats (d) it gets darker
31. 31.True or false: putting the iron away is a job for an adult. (a) False (b) True
32. 32.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
33. 33.🍋 Secret message: who does this step — writing the message? (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.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
36. 36.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) letting the paper dry (d) writing the message
37. 37.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) writing the message (c) dipping the cotton bud (d) reading the message
38. 38.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) putting the iron away (d) ironing the paper
39. 39.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) how dark the writing is (c) the kind of juice

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